Vol. 1 (4), 2014, 112‒122

Online available since 2014/ December /07 at www.oricpub.com

© (2014) Copyright ORIC Publications

Journal of Chemistry and Materials Research

Vol. 1 (4), 2014, 112122

JCMR

Journal of Chemistry and

Materials Research

ORICPublications

www.oricpub.com

www.oricpub.com/jcmr

Original Research

New Materials Based on Acridine: Correlation Structure – Properties

and Optoelectronic Applications

Hayat Sadki 1

, Samir Chtita 2

, Mohammed Naciri Bennani 1

, Tahar Lakhlifi 2

, Mohammed Bouachrine 3,

*

1 LME, Faculty of Science, University Moulay Ismail, Meknes, Morocco

2 L.C.S.N. Faculty of Science, University Moulay Ismail, Meknes, Morocco

3 MEM, High School of Technology (ESTM), University Moulay Ismail, Meknes, Morocco

Received 11 October 2014; accepted 18 October 2014

Abstract

This paper is mainly about the theoretical investigations of the structural, optoelectronic and photovoltaic properties of sixteen conjugated

compounds based on acridine. The quantum chemical calculations based on density functional theory (DFT) at B3LYP method with 6‒31G (d)

basis set for all atoms is used as a measure to investigate the theoretical ground-state geometry and electronic structure of the pre-mentioned

materials. Furthermore, Gaussian 09 program package was used as a program to get the calculations done; the results were strengthened

through the use of Gauss View 5.0. This paper also discussed the effect of different other substituent groups branched to the acridine ring on

the geometries and electronic properties of these materials in order to investigate and then understand the relationship between molecular

structure and optoelectronic properties. As a method of calculation, the TD‒B3LYP/6‒31G (d) method was used to calculation the absorption

properties (λmax, Ea, OS) of such compounds. The S1/S0 electronic excitation is said to be the highest Occupied Molecular Orbital (HOMO) to

lowest Unoccupied Molecular Orbital (LUMO) transition and it is different in terms of oscillator strength. Studying the organic solar cells can’t

be effective except if it is accompanied with a deep understanding of the theoretical knowledge of the HOMO and LUMO energy levels of the

components, for this reason the researcher has calculated and discussed the HOMO, LUMO and Gap energy Voc (open circuit voltage) of the

studied compounds. Therefore, these materials were suggested as a good candidate for organic dye-sensitized solar cells.

Keywords: π-conjugated molecules, acridine, organic solar cells, low band-gap, electronic properties, Voc (open circuit voltage).

1. Introduction

Conjugated organic oligomers and polymers were given

much consideration in areas that have to do with chemistry and

physics, and they are repeatedly studied due to their remark-

able optical and electronic properties [1,2]. Thanks to H.

Shirakawa, A.J. Heeger and A.G. Mac Diarmid’s research in

this field, for which they won the Nobel Prize in 2000, the

importance and the potentiality of this class were recently ack-

nowledged by the world scientific community [3]. The high

specific capacitance of this type of the polymers in their

* Corresponding author. Tel.: +212660736921.

E-mail address: [email protected] (M. Bouachrine).

All rights reserved. No part of contents of this paper may be reproduced or

transmitted in any form or by any means without the written permission of

ORIC Publications, www.oricpub.com.

neutral and oxidized states has stimulated suggestions for a

variety of applications such as organic light emitting diodes

(OLEDs) [4,5], field‒effect transistors [6‒8] (OTFTs), photov-

oltaic cells [9‒11], portable electronic [12], and lasers [13,14].

With a booming in research effort to develop cost-effective

renewable energy devices, dye sensitized solar cells (DSSC),

also known as Grätzel cells [15] have been the focus of

thousand of papers just in 2010 [16].

Short‒chain compounds synthesis based on conjugated

molecules has been the focus of many researchers in the field

just because they are not amorphous and can be synthesized as

well defined structures [17‒22]. On the other hand, the

invention of the ultra fast and ultra efficient photo lead to the

electron transfer between π-conjugated systems and fullerene

derivatives. Considerable interest for hetero-junction solar

cells based on interpenetrating networks of conjugated systems

and C60 derivatives has been generated [23,24]. Roquet et al.

distinguished between the nature of acceptor groups in the

molecule and the photovoltaic performance [25,26].

mailto:[email protected]

http://www.oricpub.com/

H. Sadki et al. / Journal of Chemistry and Materials Research 1 (2014) 112–122 113

Fig. 1. Chemical structure of studied compounds A (1‒4), B (1‒4), C (1‒4) and D (1‒4)

Table 1 Energy values of ELUMO (eV), EHOMO (eV), and Egap (eV) of the studied molecules obtained by B3LYP/6-31G (d) level.

Rings Studied molecules EHOMO (eV) ELUMO (eV) Egap(ELUMO ‒ EHOMO) (eV)

A

A1 -5.074 -1.276 3.798

A2 -5.284 -1.773 3.511

A3 -5.755 -2.286 3.469

A4 -4.815 -1.657 3.158

B

B1 -5.040 -1.390 3.649

B2 -5.223 -1.704 3.519

B3 -5.692 -2.149 3.543

B4 -4.772 -1.612 3.160

C

C1 -5.439 -1.192 4.247

C2 -5.611 -1.520 4.091

C3 -5.858 -2.443 3.415

C4 -5.138 -1.412 3.726

D

D1 -5.439 -1.411 4.028

D2 -5.412 -1.524 3.888

D3 -5.723 -2.573 3.150

D4 -5.201 -1.417 3.784

In the previous two decades, low band gap polymers which

are designed to better match solar output have been studied

and acridine was distinguished from anthracene, though they

are very close in structure, in terms of the nitrogen atom. Acri-

dine said to possess the nitrogen atom in its central ring. It was

widely used along with its derivatives as dyes for photovoltaic

cells organic electroluminescent diodes and fluorescent prob-

es. Therefore, acridine containing polymers combining the opt-

ical properties of acridine and the valuable properties of polyi-

mides seem to be perspective materials for optoelectronic app-

lications [27].

To benefit from their adaptive properties to photovoltaic

cells, we should understand the ultimate relations between

structure and properties of these materials. Recent experim-

ental work on these new materials together with the theoretical

efforts constitute an important source of valuable information

which complements the experimental studies, thereby to the

understanding of the molecular electronic structure as well as

the nature of absorption and photoluminescence [28‒32].

In what follows, theoretical study by using DFT method on

sixteen conjugated compound based on acridine shown in

Fig.1 is reported. Different electron side groups were introdu-

ced to investigate their effects on the electronic structure. A

systematic theoretical study of such compound has not been

reported as we know. Thus, our aim is first, to explore their

electronic and absorption properties on the basis of the DFT

quantum chemical calculations. Second, we are interested to

elucidate the parameters that influence the photovoltaic

efficiency toward better understanding of the structure–

property relationships. We think that the presented study of

structural, electronic and optical properties for these compoun-

ds could help to design more efficient functional photovoltaic

organic materials.

114 H. Sadki et al. / Journal of Chemistry and Materials Research 1 (2014) 112–122

The quantum chemical investigation has been performed to

the optical and electronic properties of a series of compounds

based on acridine. Different electron side groups were introdu-

ced to investigate their effects on the electronic structure. The

theoretical knowledge of the HOMO and LUMO energy levels

of the components is a basis in studying organic solar cells, so,

the HOMO, LUMO and Gap energy of the studied compounds

have been calculated and reported.

In this paper, sixteen compounds based on acridine A

(1‒4), B (1‒4), C (1‒4) and D (1‒4) (shown Fig. 1), are

designed. The geometries, electronic properties, absorption

and emission spectra of these studied compounds are studied

by using density functional theory (DFT) and time‒dependent

density functional theory (TD/DFT) with the goal to find

potential sensitizers for use in organic solar cells.

2. Materials and Methods

All computations of the studied compounds in this work

were carried out with the Gaussian 09 program package [33]

on an Intel Pentium IV 3.3 GHz PC running Linux supported

by Gauss View 5.0 [34]. These methods are widely used beca-

use they can lead to similar precision to other methods and beca-

use they are also less demanding and time saving from the compu-

tational point of view. Using the B3LYP functional [Becke’s

three‒parameter functional (B3) and includes a mixture of HF

with DFT exchange terms associated with the gradient corre-

cted correlation functional of Lee, Yang and Parr (LYP)] exch-

ange correlation functional [35,36]. The 6‒31G (d) basis set

was chosen as a compromise between the quality of the theoreti-

cal approach and the high computational cost associated with the

high number of dimensions to the problem for all atoms [37,38].

A1 A2 A3 A4

B1 B2 B3 B4

C1 C2 C3 C4

D1 D2 D3 D4

Fig. 2. Optimized geometries obtained by B3LYP/6-31G (d) of the studied molecules


Gauss View software program (version 3.07) and the

graphical molecular orbital were used to generate the 3D

structures of the molecules. The HOMO, LUMO and gap’s

energies were also deduced from the stable structure of the

neutral and doped forms, where the Egap is evaluated as the

difference between LUMO and HOMO energies. In this paper,

the transition energies were calculated at the ground-state and

excite‒state geometries using TD‒DFT calculations on the

fully optimized geometries. And the results obtained gave us

the absorption and emission maxima, their corresponding

transition energies, and the factor oscillation.

Finally, the nature and the energy of vertical electron

transitions (the main singlet–singlet electron transitions with

highest oscillator strengths) of molecular orbital wave functi-

ons were presented. Then, the theoretical simulated absorption

spectrum was calculated using the S. Wizard program [39].

The electronic absorption in vacuum was carried out using

CIS/TD DFT (B3LYP/6‒31G (d)) method on the basis of the

optimized ground and excited structures, respectively [40].

3. Results and discussion

3.1. Geometry optimization

Fig. 1 presents the sketch map of studied structures while

Fig. 2 depicts the optimized geometries obtained by

B3LYP/6‒31G (d) of the studied molecules. The findings of

the optimized structures show that they have similar

conformations (quasi planar conformation). And it is found

also that the modification of several groups attached to the

acridine does not change the geometric parameters.

3.2. Optoelectronic properties

The optoelectonic properties depend essentially on the

appropriate HOMO and LUMO energy levels and the electron

and hole mobilities. Everyone knows that (Egap) between the

highest occupied molecular orbital (HOMO) and the lowest

unoccupied molecular orbital (LUMO) is an essential

parameter that determines the molecular admittance since it is

a measure of the electron density hardness. The band gap is

estimated as the difference between the HOMO and the

LUMO level energies (Eg = ∆EHOMO–ELUMO) on the ground

singlet state. The results of the experiment showed that the

HOMO and LUMO energies were obtained from an empirical

formula based on the onset of the oxidation and reduction

peaks measured by cyclic voltametry [41,42]. However,

theoretically speaking the HOMO and LUMO energies can be

calculated by DFT method of calculation. It is remarkable that

the solid‒state packing effects are not calculated in DFT

calculations, this fact affects the HOMO and LUMO energy

levels in a thin film compared to an isolated molecule as

considered in the calculations. Though these calculated energy

levels lack some accuracy still we can use them to get

information by comparing similar oligomers or polymers [43].

The theoretical electronic properties parameters (EHOMO,

ELUMO and Gap) are listed in Table 1. This table also clearly

shows the effect of the different other substituent groups

branched to the acridine ring on the HOMO and LUMO

energies. This implies that different side substituent structures

play key role in electronic properties and the effect of slight

structural variations. In addition the calculated band gap (Egap)

of the studied compounds increases in the following order:

D3 < A4 < B4 < C3 < A3 < A2 < B2 < B3 < B1 C4 < D4<

A1 < D2 < D1 < C2 < C1

3.3. Frontier molecular orbitals

The frontier molecular orbital (MO) contribution is of a

high importance in determining the charge‒separated states of

the studied molecules because the relative ordering of

occupied and virtual orbital provides a reasonable qualitative

indication of excitation properties and provides also the ability

of electron hole transport. The iso‒density plots of the model

compounds are shown in Fig. 2. In general, and as plotted in

this figure (LUMO, HOMO), the HOMOs of these oligomers

in the neutral form possess a π‒bonding character within

subunit and a π‒antibonding character between the consecutive

subunits. On the other hand, the LUMO of all studied

compounds generally possess a π‒antibonding character within

subunit and a π‒bonding character between the subunits. This

implies that the singlet excited state involving mainly the

promotion of an electron from the HOMO to the LUMO

should be more planar. The HOMO is delocalized along the

four radical R through the π‒conjugated bridges group. The

LUMO is delocalized in the aciridine ring. The examination of

the HOMO and LUMO of the three organic dyes indicates that

HOMO→LUMO excitation moves the electron distribution

from the R radical to the acridine group.

3.4. Photovoltaic properties

To evaluate the possibilities of electron transfer from the

excited studied molecules to the conductive band of the

acceptor PCBM the HOMO and LUMO levels were

compared. Generally, the most efficient material solar cells are

based on the bulk hetero‒junction structure of the blend of

π‒conjugated molecule or polymer donors and fullerene

derivative acceptors. Here, we studied the photovoltaic

properties of the compounds A(1‒4), B(1‒4), C(1‒4) and

D(1‒4) as donor blended with [6.6]‒phenyl‒C61‒butyric acid

methyl ester (PCBM), which are the most broadly used as an

acceptor in solar cell devices. The HOMO and the LUMO

energy levels of the donor and acceptor components are very

important factors to determine whether effective charge

transfer will happen between donor and acceptor. As shown in-


Table 2 Energy values of ELUMO (eV), EHOMO (eV), Egap (eV), α and the open circuit voltage Voc (eV) of the studied molecules obtained

by B3LYP/6-31G (d) level.

PCBM C60 (A) PCBM C60 PCBM C70 PCBM C76

Compounds EHOMO (ev) ELUMO (ev) Egap (ev) Voc (ev) ev Voc (ev) ev Voc (ev) ev Voc (ev) ev

A1 -5.074 -1.276 3.798 1.074 2.424 1.304 2.194 1.234 2.264 0.984 2.514

A2 -5.284 -1.773 3.511 1.284 1.927 1.514 1.697 1.444 1.767 1.194 2.017

A3 -5.755 -2.286 3.469 1.755 1.414 1.985 1.184 1.915 1.254 1.665 1.504

A4 -4.815 -1.657 3.158 0.815 2.043 1.045 1.813 0.975 1.883 0.725 2.133

B1 -5.040 -1.390 3.649 1.040 2.310 1.270 2.080 1.200 2.150 0.950 2.400

B2 -5.223 -1.704 3.519 1.223 1.996 1.453 1.766 1.383 1.836 1.133 2.086

B3 -5.692 -2.149 3.543 1.692 1.551 1.922 1.321 1.852 1.391 1.602 1.641

B4 -4.772 -1.612 3.160 0.772 2.088 1.002 1.858 0.932 1.928 0.682 2.178

C1 -5.439 -1.192 4.247 1.439 2.508 1.669 2.278 1.599 2.348 1.349 2.598

C2 -5.611 -1.520 4.091 1.611 2.180 1.841 1.950 1.771 2.020 1.521 2.270

C3 -5.858 -2.443 3.415 1.858 1.257 2.088 1.027 2.018 1.097 1.768 1.347

C4 -5.138 -1.412 3.726 1.138 2.288 1.368 2.058 1.298 2.128 1.048 2.378

D1 -5.439 -1.411 4.028 1.439 2.289 1.669 2.059 1.599 2.129 1.349 2.379

D2 -5.412 -1.524 3.888 1.412 2.176 1.642 1.946 1.572 2.016 1.322 2.266

D3 -5.723 -2.573 3.150 1.723 1.127 1.953 0.897 1.883 0.967 1.633 1.217

D4 -5.201 -1.417 3.784 1.201 2.283 1.431 2.053 1.361 2.123 1.111 2.373

PCBM C60

(A) -6.1 -3.700

PCBM C60 - -3.470

PCBM C70 - -3.540

PCBM C76 - -3.790

-6

-5

-4

-3

-2

-1

PCBM C60

HOMO

LUMO A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

D1

D2

D3

D4

PCBM C60

En

erg

y L

ev

el(

eV

)

Eg

A3=

3.4

69

Eg

C4=

3.7

26

Eg

C3=

3.4

15

Eg

C2=

4.0

91

Eg

C1=

4.2

47

Eg

B4=

31

60

Eg

B3=

3.5

43

Eg

B2=

3.5

19

Eg

B1=

3.6

49

Eg

A4=

3.1

58

Eg

A1=

3.7

98

Eg

A2=

3.5

11

Eg

D1=

4.0

28

Eg

D2=

3.8

88

Eg

D3=

3.1

50

Eg

D4=

3.7

84

Fig. 3. Sketch of B3LYP/6-31G (d) calculated energies of the HOMO, LUMO level of studied molecules.

Table 2, the change of the electron-donor shows a great effect

on the HOMO and LUMO levels. Fig. 3 shows detailed data of

absolute energy of the frontier orbitals for the studied

compounds and PCBM derivatives. It is deduced that the

nature of donor or acceptor pushes up/down the HOMO/

LUMO energies in agreement with their electron character.

Table 2 lists the calculated frontier orbital energies and

energy Egap between highest occupied molecular orbital

(HOMO) and lowest unoccupied molecular orbital (LUMO)

and the Egap energy of the studied molecules, also the open

circuit voltage Voc (eV) and The difference between both the

energy levels LUMO of the donor and acceptor α [44].


Table 3 The contour plots of HOMO and LUMO orbitals of all studied compounds obtained by B3LYP/6- 31G (d).

Compounds Contour Plots

HOMO LUMO

A1

A2

A3

A4

B1

B2

B3

B4


C1

C2

C3

C4

D1

D2

D3

D4


On the other hand and from the above analysis, we know

that the LUMO energy levels of the studied compounds are

much higher than that of the ITO conduction band edge (‒4.7

eV). Thus, the studied molecules A(1‒4), B(1‒4), C(1‒4) and

D(1‒4) have a strong ability to inject electrons into ITO

electrodes. The experiment phenomenon is quite consistent

with previous literature [45], this latter reported that the

increase of the HOMO levels may suggest a negative effect on

organic solar cell performance due to the broader gap between

the HOMO level of the organic molecules and the HOMO

level of several acceptor PCBM. (C60, C70, C76) (Fig. 4).

It is known that the architecture of photoactive layer is one

of the principle factors of efficiencies of solar cells. The most

efficient technique to generate free charge carriers is bulk

hetero-junction where the π‒conjugated compounds donors are

blended with fullerene derivatives us acceptor [46]. In our

study, PCBM and derivatives (C60, C70, C76) were included

for comparison purposes.

As shown in Table 3, both HOMO and LUMO levels of

the studied molecules agree well with the requirement for an

efficient photosentizer. It should be noted that the LUMO

levels of all studied compounds are higher than that of PCBM

derivatives which varies in literature from ‒4.0 to ‒3.47 eV

(C60 (‒3.47 eV) ;C70 (‒3.54 eV); C76 (‒3.79 eV) [47].

The most effcient cell design, leading to the highest power

conversion effciencies, is the bulk‒heterojunction (BHJ) solar

cell [48,49]. The active layer of BHJ solar cells consists of an

interpenetrating network of two types of organic materials, an

electron donor and an electron acceptor, and is formed through

the control of the phase separation between the donor and

acceptor parts in the bulk. Accordingly, the large donor

acceptor area can favour charge separation and, hence,

increases the conversion effciency of the cell [50].

On the other hand and knowing that in organic solar cells,

the open circuit voltage is found to be linearly dependent on

the HOMO level of the donor and the LUMO level of the

acceptor [51,52]. The power conversion efficiency (PCE) was

calculated according to the following equation (1):

PCE = 1/Pin (FF. Voc. Jsc) (1)

where Pin is the incident power density, Jsc is the short‒circuit

current, Voc is the open-circuit voltage, and FF denotes the fill

factor.

To evaluate the possibilities of electron transfer from the

studied molecules to the conductive band of the proposed

acceptors, the HOMO and LUMO levels are compared.

Knowing that in organic solar cells, the open circuit voltage is

found to be linearly dependent on the HOMO level of the

donor and the LUMO level of the acceptor. The maximum

open circuit voltage (Voc) of the Bulk Hetero Junction solar

cell is related to the difference between the highest occupied

molecular orbital (HOMO) of the electron donor (A(1‒4),

B(1‒4), C(1‒4) and D(1‒4)) and the LUMO of the electron

acceptor (PCBM derivatives), taking into account the energy

lost during the photo‒charge generation [53‒55]. The

theoretical values of open‒circuit voltage Voc have been

calculated from the following expression (2):

Voc =│EHOMO (Donnor)│–│ELUMO (Acceptor)│‒ 0.3 (2)

The theoretical values of the open circuit voltage Voc of the

studied compounds calculated according to the equation (2)

range from (0.772 to 1.858 eV) for PCBM C60(A); (1.045 to

2.088 eV) for PCBM C60; (0.932 to 2.018 eV) for PCBM C70

and (0.682 to 1.768 eV) for PCBM C76 (Table 4).

Table 4 Main transition states, their assignments, the corresponding wavelength and oscillator strength for all compounds have been obtained

by using TD-DFT//B3LYP/6-31G (d) levels

Compounds Transition Wavelength (λ, nm) Ea (eV) O.S MO/character

A1 S0→S1 287.50 117,34 0.1493 HOMO→LUMO+1 (40%)

A2 S0→S1 408.97 82,49 0.3206 HOMO→LUMO (91%)

A3 S0→S1 404.58 83,38 0.5959 HOMO→LUMO (83%)

A4 S0→S1 450.13 74,947 0.2925 HOMO→LUMO (93%)

B1 S0→S1 271.69 124,17 0.2062 HOMO→LUMO+2 (50%)

B2 S0→S1 313.26 107,69 0.8078 HOMO→LUMO+1 (72%)

B3 S0→S1 386.73 87,23 0.2688 HOMO→LUMO (82%)

B4 S0→S1 333.43 101,18 0.7123 HOMO→LUMO+1 (84%)

C1 S0→S1 299.89 112,49 0.1039 HOMO-1→LUMO (75%)

C2 S0→S1 329.41 102,413 0.5828 HOMO-1→LUMO (78%)

C3 S0→S1 360.48 93,59 0.7212 HOMO-1→LUMO (98%)

C4 S0→S1 367.88 91,70 0.4184 HOMO→LUMO (94%)

D1 S0→S1 241.17 139,88 0.6290 HOMO-3→LUMO (61%)

D2 S0→S1 363.67 92,76 0.1742 HOMO→LUMO (84%)

D3 S0→S1 357.49 94,37 0.1404 HOMO→LUMO+1 (79%)

D4 S0→S1 373.18 90,40 0.1785 HOMO→LUMO (96%)


These values are sufficient for a possible efficient electron

injection. Therefore, all the studied molecules can be used as

organic solar cell sensitizers because the electron injection

process from the excited molecule to the conduction band of

the acceptor (PCBM derivatives) and the subsequent

regeneration is possible. We noted that the best values of Voc

are indicated for the studied compounds blended with C60 or

C70 and higher value are given for compound C3 (2.088 eV)

and (2.018 eV) blended with C60 and C70 respectively.

3.5. Absorption properties

The absorption properties of a new material matches with

the solar spectrum is an important factor for the application as

a photovoltaic material, and a good photovoltaic material

should have broad and strong visible absorption characteri-

stics. The TD‒DFT method has been used on the basis of the

optimized geometry to obtain the energy of the singlet–singlet

electronic transitions and absorption properties (λmax) of

A(1‒4), B(1‒4), C(1‒4) and D(1‒4). The corresponding

simulated UV‒Vis absorption spectra of all studies

compounds, presented as oscillator strength against

wavelength are shown in Fig. 5. As illustrated in Table 4, we

can find the values of calculated absorption λmax (nm) and

oscillator strength (O.S) along with main excitation

configuration of all studied compounds.

The calculated wave length λabs of the studied compounds

decreases in the following order:

A4 > A2 > A3 > B3 > D4 > C4 > D2 > C3 > D3 > B4 >

C2 > B2 > C1 > A1 > B1 > D1

This bathochromic effect from D1 (λmax = 241.17 nm) to

A4 (λmax =450.13nm) is obviously due to a higher mean

conjugation length and to inter-chain electronic coupling [56]

and to the effect of the different other substituent groups

branched to the Acridine ring. Those interesting points are

seen both in the studying the electronic and absorption

properties.

In addition, we note that the broader absorption peak

means that there is a distribution of energy level corresponding

to the π→π* transition. This interesting point is seen both by

analyzing electronic and absorption results. Excitation to the

S1 state corresponds exclusively to the promotion of an

electron from the HOMO to the LUMO. As in the case of the

oscillator strength, the absorption wavelengths arising from

S0→S1 electronic transition increase progressively with the

increasing of conjugation lengths. It is reasonable, since

HOMO→LUMO transition is predominant in S0→S1

electronic transition; the results are a decrease of the LUMO

and an increase of the HOMO energy.

C60 C70 C76

Fig. 4. Structure of the investigated fullerenes

100 200 300 400 500 600

Wavelength (nm)

Ab

sorb

ance

(a.

u)

A1

A2

A3

A4

B1

B2

B3

B4

100 200 300 400 500

Wavelength (nm)

Ab

sorb

ance

(a.

u)

C1

C2

C3

C4

D1

D2

D3

D4

Fig. 5. Simulated UV-visible optical absorption spectra of title compounds with the calculated data at the TD-DFT/B3LYP/6-31G (d) level.


4. Conclusions

In this study, we have used the Density Functional Theory

DFT method and 6‒31G (d) basis set at density functional

B3LYP level to investigate theoretical analysis on the

geometries and electronic properties of sixteen compounds

based on the acridine ring which displays the effect of

substituted groups on the structural and optoelectronic

properties of these materials and leads to the possibility to

suggest these materials for organic solar cells application and

in order to guide the synthesis of novel materials with specific

electronic properties. The concluding remarks are:

The results of the optimized structures for all studied

compounds so that they have similar conformations (quasi

planar conformation). We found that the modification of

several groups does not change the geometric parameters.

The calculated frontier orbital energies HOMO level,

LUMO level, and band gap of the studied compounds

were well controlled by the different other substituent

groups branched to the acridine ring. The calculated band

gap Egap of the studied molecules was in the range 3.150‒

4.247 eV.

The energy Egap of molecule D3 (3.150eV) is much

smaller than that of the other compounds.

The best values of Voc are indicated for the studied

compounds blended with C60 or C70 and higher value are

given for compound C3 (2.088 eV) and (2.018 eV)

blended with C60 and C70 respectively.

The UV‒Vis absorption properties have been obtained by

using TD/DFT calculations. The obtained absorption

maximums are in the range 241.17 to 450.13 nm.

These obtained values are sufficient for a possible efficient

electron injection. Therefore, all the studied molecules can be

used as sensitizers because the electron injection process from

the excited molecule to the conduction band of the acceptor

and the subsequent regeneration is possible in organic

sensitized solar cell.

Finally, the procedures of theoretical calculations can be

employed to predict the electronic properties on the other

compounds, and further to design novel materials for organic

solar cells.

Acknowledgement(s):

This work has been supported by the project Volubilis AI

n°: MA/11/248 and by CNRST/CNRS cooperation (Project

Chimie 10/09). We are grateful to the “Association Marocaine

des Chimistes Théoriciens” (AMCT) for its pertinent help

concerning the programs.

References

[1] Heeger, A.J. (2001). Semiconducting and metallic polymers: the fourth

generation of polymeric materials –nobel lecture, December 8, 2000;

Leclerc, M. Can. Chem. News., 53, 26; Handbook of Conducting

Polymers, 2nd edition.

[2] Skotheim, T. A., Elsenbaumer, R. L., Reynolds, J. R., Eds. (1998).

Marcel Dekker: New York.

[3] Novak, P., Muller, K., Santhanam, K.S.V.; Haas, O., (1997). Chem.

Rev., 97, 207. DOI: 10.1021/cr941181o.

[4] Friend, R.H., Gymer, R.W., Holmes, A.B., Burroughes, J.H., Markes,

R.N., Taliani, C., Bradley, D.D.C., Santos, D.A.D., Bredas, J.L.,

Logdlund, M. and Salaneck, W.R. (1999). “Electroluminescence in

conjugated polymers”, Nature, vol. 397, pp. 121-128.

[5] Chang, C.C., Pai, C.L., Chen, W.C. and Jenekhe, S.A. (2005). “Spin

Coating of Conjugated Polymers for Electronic and Optoelectronic

Applications”, Thin Solid Films, vol. 479, pp. 254–260.

[6] Dimitrakopoulos, C.D. and Malenfant, P.R.L., (2002). “Organic Thin

Film Transistors for Large Area Electronics”, Adv. Mater., vol. 14, pp.

99-117.

[7] Katz, H.E. and Bao, Z., (2000). “The Physical Chemistry of Organic

Field-Effect Transistors”, J. Phys. Chem. B, vol. 104, pp. 671-678.

[8] Horowitz, G., (1998). “Organic Field-Effect Transistors”, Adv. Mater.,

vol. 10, pp. 365-377.

[9] Hou, J., Yang, C., Qiao, J., Li, Y., (2005). “Synthesis and photovoltaic

properties of the copolymers of 2-methoxy-5-(2′-ethylhexyloxy)-1,4-

phenylene vinylene and 2,5-thienylene-vinylene”, Synth. Met., vol. 150,

pp. 297–304.

[10] Yang, C., Li, H., Sun, Q., Qiao, J., Li, Y. and Zhu, D., (2005)

“Photovoltaic cells based on the blend of MEH-PPV and polymers with

substituents containing C60 moieties”, Sol. Energy Mater. Sol. Cells,

vol. 85, pp. 241–249.

[11] Colladet, K., Nicolas, M., Goris, L., Lutsen, L. and Vanderzande, D.,

(2004). “Low-band gap polymers for photovoltaic applications”, Thin

Solid Films, vol. 451, pp. 7–11.

[12] Kim, Y.S., Ha, S.-C., Yang, Y., Kim, Y.J., Cho, S.M., Yang, H. and

Kim, Y.T., (2005). “Portable electronic nose system based on the carbon

black-polymer composite sensor array”, Sens. Actuators B, vol. 108, pp.

285–291.

[13] Ghosh, D., Samal, G.S., Biswas, A.K., Mohapatra, Y.N., (2005). “Laser-

induced degradation studies of photoluminescence of PPV and CNPPV

thin films”, Thin Solid Films, vol. 477, pp. 162 168.

[14] Schrader, S., Penzkofer, A., Holzer, W., Velagapudi, R. and Grimm, B.,

(2004). “Laser spectroscopic investigation of a new precursor-type

polyparaphenylenevinylene”, J. Lumin., vol. 110, pp. 303–308.

[15] O'Regan, B, Gratzel, M (1991). A low-cost, high-efficiency solar cell

based on dye-sensitized colloidal TiO2 films. Nature, 353 (6346), 737-

740.

[16] Peter, LM., (2011). The Grätzel Cell: Where Next?, The Journal of

Physical Chemistry Letters 2 (15), 1861-1867. Doi:10.1021/jz200668q.

[17] Velusamy, M., Thomas, K.R.J., Lin, J.T., Hsu, Y., Ho, K., (2005).

Organic dyes incorporating low-band-gap chromophores for

dyesensitized solar cells. Org. Lett. 7, 1899.

[18] Mullen, K., Wegner, G. (Eds.), (1998). Electronic Materials: The

oligomers Approach. Wiley-VCH, Weinheim, New York (p. 105).

[19] Cornil, J., Beljonne, D., Bre´das, J.L., Mullen, K., Wegner, G., (1998).

Electronic Materials: The oligomers Approach. Wiley-VCH, Weinheim,

New York, p. 432.

[20] Li, X.-G., Li, Ji., Huang, M-R., (2009). Facile optimal synthesis of

inherently electroconductive polythiophene nanoparticles. Chem. Eur. J

15, 6446.

[21] Li, X.-G., Li, Ji. Meng, Q.-K., Huang, M.-R., (2009). Interfacial

synthesis and widely controllable conductivity of polythiophene

microparticles. J. Phys. Chem. B 113, 9718.

[22] Li, X.-G., Liu, Y.-W., Huang, M.-R., Peng, S., Gong, L.-Z. and

Moloney, M.G., (2010). Simple efficient synthesis of strongly

luminescent Polypyrene with intrinsic conductivity and high Carbon


yield by chemical oxidative polymerization of Pyrene. Chem. Eur. J.,

16, 4803.

[23] Shaheen, S.E., Brabec, C.J., Sariciftci, N.S., Padinger, F., Fromherz, T.,

Hummelen, J.C., (2001), Organic photovoltaic devices produced from

conjugated polymer/ methanofullerene bulk heterojunctions. Synth.

Met. 121, 1517.

[24] Padinger, F., Rittberger, R., Sariciftci, N.S., (2003). Effects of

postproduction treatment on plastic solar cells. Adv. Funct. Mater. 13,

85.

[25] Roquet, S., Cravino, A., Leriche, P., Aleveque, O., Frere, P., Roncali, J.,

(2006). Triphenylamine Thienylenevinylene hybrid systems with

internal charge transfer as donor materials for heterojunction solar cells.

J. Am. Chem. Soc., 128, 3459.

[26] He, Y.J., Chen, H.-Y., Hou, J.H., Li, Y.F., (2010). Indene-C60

bisadduct: a new acceptor for high performance polymer solar cells. J.

Am. Chem. Soc. 132, 1377.

[27] Shengang, X., Mujie, Y., Shaokui, C. (2007). Polymer, 48 2241.

[28] Bouzakraoui, S., Bouzzine, S. M., Bouachrine, M., Hamidi, M. (2005).

J. Mol. Struct. (Theochem), 725, 39–44.

[29] Bouzakraoui, S., Bouzzine, S. M., Bouachrine, M., Hamidi, M. (2006).

Energy Mater. & Sol. Cells, 90, 1393–1402.

[30] Zgou, H., Bouzzine, S. M., Bouzakraoui, S., Hamidi, M., Bouachrine,

M. (2008). Chin. Chem. Lett., 19, 123–126.

[31] Bouzzine, S. M., Makayssi, A., Hamidi, M., Bouachrine, M. (2008). J.

Mol. Struct. (Theochem). 851, 254–262.

[32] Mondal, R., Becerril, H. A., Verploegen, E., Kim, D., Norton, J. E., Ko

S., Miyaki, N., Lee S., Toney, M. F., Bredas, J.-L., McGehee, M. D.,

Bao, Z. (2010). J. Mater. Chem., 20, 5823–5834.

[33] Frisch, M.J., Trucks, G.W., Schlegel, H.B., Scuseria, G.E., Robb, M.A.,

Cheeseman, J.R., Montgomery, J.A., Vreven, T. Jr., Kudin, K.N.,

Burant, J.C., Millam, J.M., Iyengar, S.S., Tomasi, J., Barone, V.,

Mennucci, B., Cossi, M., Scalmani, G., Rega, N., Petersson, G.A.,

Nakatsuji, H., Hada, M., Ehara, M., Toyota, K., Fukuda, R., Hasegawa,

J., Ishida, M., Nakajima, T., Honda, Y., Kitao, O., Nakai, H., Klene, M.,

Li, X., Knox, J.E., Hratchian, H.P., Cross, J.B., Adamo, C., Jaramillo,

J., Gomperts, R., Stratmann, R.E., Yazyev, O., Austin, A.J., Cammi, R.,

Pomelli, C., Ochterski, J.W., Ayala, P.Y., Morokuma, K., Voth, G.A.,

Salvador, P., Dannenberg, J.J., Zakrzewski, V.G., Dapprich, S., Daniels,

A.D., Strain, M.C., Farkas, O., Malick, D.K., Rabuck, A.D.,

Raghavachari, K., Foresman, J.B., Ortiz, J.V., Cui, Q., Baboul, A.G.,

Clifford, S., Cioslowski, J., Stefanov, B.B., Liu, G., Liashenko, A.,

Piskorz, P., Komaromi, I., Martin, R.L., Fox, D.J., Keith, T., Al-Laham,

M.A., Peng, C.Y., Nanayakkara, A., Challacombe, M., Gill, P.M.W.,

Johnson, B., Chen, W., Wong, M.W., Gonzalez, C., Pople, J.A.,

Gaussian, Inc., Pittsburgh, PA, (2003).

[34] Dennington, R., Keith, T., Millam, J., GaussView, Version 5.0,

Semichem Inc. KS, (2005).

[35] Becke, A.D. (1993). J. Chem. Phys., 98, 5648.

[36] Lee C., Yang, W., Parr, R.G. (1988). Phys. Rev. B 37, 785.

[37] Casida, M. E., Jamorski, C., Casida, K. C., Salahu, D. R. (Mar. 1998),

.J. Chem. Phys., Vol. 108, Issue 11, pp. 4439−4449.

[38] Stratmann, R. E., Scuseria, G. E., Frisch, M. J. (Nov. 1998). J. Chem.

Phys., Vol. 109, Issue 19, pp. 8218−8224.

[39] Gorelsky, S.I. SWizard program, University of Ottawa, Canada, (2009).

<http:// www.sg-chem.net/>

[40] Yang, L., Ren, A.M., Feng, J.K., Ma, Y.G., Zhang, M., Liu, X.D., Shen,

J.C., Zhang, H.X., et al. (2004) . J. Phys. Chem., 108, 6797.

[41] Bredas, J.L.; Silbey, R.; Boudreaux, D.S.S., Chance, R.R. (1983). J.

Am Chem. Soc., 105, 6555.

[42] Grozema, F.C.; Candeias, L.P.; Swart, M.; Van Duijnen, P.; Wildemen,

J.; Hadzianon, G. (2002). J. Chem. Phys., 117, 11366.

[43] Huang, J.; Niu, Y.; Yang, W; Mo, Y; Yang, M.; Cao, Y., (2002).

Macromolecules, 35, 6080.

[44] Abram, T., Zgou, H., Bejjit, L., Hamidi, M., Bouachrine, M. (2014). “

Design of New Small Molecules based on Thiophene and Oxathiazole

for bulk Heterojunction Solar cells: a Computational Study,”

International Journal of Advanced Research in Computer Science and

Software Engineering, vol 4, pp. 742-750.

[45] Zhang, L., Zhang, Q., Ren H., Yan, H., Zhang, J., Zhang, H., Gu, J.

(Dec. 2007). “Calculation of band gap in long alkyl-substituted

heterocyclicthiophene-conjugated polymers with electron donor–

acceptor fragment,” J. Solar Energy Materials & Solar Cells., vol. 92,

pp. 581–587.

[46] Derouiche, H., Djara, V. (Mar. 2007). “Impact of the energy difference

in LUMO and HOMO of the bulk heterojunctions components on the

efficiency of organic solar cells” J. Solar Energy Materials & Solar

Cells., vol. 91, pp. 1163–1167.

[47] Morvillo, P. (July.2009). “Higher fullerenes as electron acceptors for

polymer solar cells: A quantum chemical study” J. Solar Energy

Materials & Solar Cells., vol. 93, pp.1827–1832

[48] Yu, G., Gao, J., Hummelen, J. C., Wudl, F. and Heeger, A. J.

(Dec.1995). “Polymer Photovoltaic Cells: Enhanced Efficiencies via a

Network of Internal Donor-Acceptor Heterojunctions,” J. science.,

vol.270, pp.1789-1791.

[49] Halls, J. J. M., Pichler, K., Friend, R. H., Moratti, S. C. and Holmes, A.

B. (Avr. 1996). “Exciton diffusion and dissociation in a poly(π--

phenylenevinylene)/C60 heterojunction photovoltaic cell,” J. Appl.

Phys. Lett., vol. 68, pp. 3120.

[50] Amro, K., Thakur, A.K., Rault-Berthelot, J., Poriel, C., Hirsch, L.,

Douglas, W.E., Clément, S. and Gerbier, P. (Nov. 2012). “2,5-

Thiophene substituted spirobisiloles -synthesis, characterization,

electrochemical properties and performance in bulk heterojunction solar

cells,” New J. Chem., vol. 37, pp. 464-473.

[51] He, Y., Chen, H.-Y., Hou, J., Li Y. (2010), J. Am. Chem. Soc. 132,

1377–1382.

[52] Kooistra, F. B., Knol, J., Kastenberg, F., Popescu, L. M., Verhees, W. J.

H., Kroon, J. M., Hummelen, J. C. (2007). Org. Lett. 9, 551–554.

[53] Gadisa, A., Svensson, M., Anderson, M. R., Inganas, O. (2004). Appl.

Phys. Lett., 84 1609–1611.

[54] Scharber, M. C., Mühlbacher, D., Koppe, M., Denk, P., Waldauf, C.,

Heeger, A. J., Brabec, C. J. (2006). Adv. Mater. 18, 789–794;

[55] Brabec, C. J., Cravino, A., Meissner, D., Sariciftci, N. S., Fromherz, T.,

Rispens, M.T., Sanchez, L., Hummelen, J.C. (2001). Adv. Funct. Mater,

11, 374–374.

[56] Jia, C., Zhang, J., Bai, J., Zhang, L., Wan, Z., Yao, X. (2012). Dyes and

Pigments, 94, 403-409.

http://www.sg-chem.net/