187 

This work is licensed under a Creative Commons Attribution 4.0 International License 

 IHJPAS. 37 (1) 2024 

Ibn Al-Haitham Journal for Pure and Applied Sciences 

Journal homepage: jih.uobaghdad.edu.iq 

PISSN: 1609-4042, EISSN: 2521-3407 

   

 
1,2Department of Physics, College of Education for Sciences Ibn-AL-Haitham, University of Baghdad, 

Baghdad, Iraq. 
3Department of Solid-State Physics, Faculty of Basic Sciences, University of Mazandaran,Babolsar, Iran.  

 
 

*Corresponding Author. Naeem.Nahi1104a@ihcoedu.uobaghdad.edu.iq 

 

 
 

 

Abstract  

In this research, we investigate and evaluate the efficiency of a hetero junction N749-TiO2 device 

based on a simple donor-acceptor model for electron transfer. Electron transfer from a photo-

excited N749 sensitized into a wide-band gap TiO2 is the basic charge separation in dye-sensitized 

solar cells, or "DSSCs". Due to the understanding of the current of the DSSCs functioning 

mechanism, the energy levels of the hetero junction N749-TiO2 device surrounded by DCM 

solvent as polar media must be continuum levels. The current-voltage (J-V) characteristics of the 

N749-TiO2 device are calculated in two concentrations at room temperature (T=300 k) and 100
mW

Cm2  

irradiation. The fill factor and efficiency of the device are found to be 0.134 and 6.990 for 

concentration 3.5 × 1018 (
1

𝑐𝑚3 
) compared to 0.146 and 9.974 for concentration 4.5 × 1018(

1

𝑐𝑚3 
). 

The efficiency of the N749-TiO2 device is in agreement with experimental results. It also offers a 

rational for the suggestion to use the application of N749-TiO2 high-performance solar cells. 

 

Keywords: Efficiency, N749 Dye , TiO2,  Dye Sensitized  Solar Cell  

  

1. Introduction  

Energy use continues to increase, increasing the depletion of fossil resources and increasing 

greenhouse gas emissions, which has driven tremendous efforts to provide more clean and 

renewable energy [1]. The dye-sensitized solar cells DSSC photovoltaic solar cell technology has 

drawn wide attention due to its simple fabrication process, low cost, and higher photovoltaic 

efficiency [2]. The DSSCs convert the sunlight into electric energy when excited  the dye by 

absorbing the light to trigger a charge transition from the sensitized dye into the conduction band 

of the TiO2, and regenerating oxidized dye molecules by the electron donation from the redox 

couple in the system. Finally, the electron transfer through the load completed the circuit [3]. The 

donor-acceptor model is one of the simplest models used to discuss the electron transfer, which 

neither forms nor breaks any chemical bond in the system [4]. The electronic transfer reaction 

Received: 17 March 2023, Received 25 April 2023, Accepted 3 May 2023, Published 20 January 2024 

 

 

Determining of Efficiency for the N749 Dye Contact with 𝐓𝐢𝐎𝟐 
in Dye Sensitized Solar Cell 

 

doi.org/10.30526/37.1.3235 

 

 1Naeem Nahi  Abd ALI*   2Hadi J. M. Al-Agealy  3Hossain Milani Moghaddam  

https://creativecommons.org/licenses/by/4.0/
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mailto:Naeem.Nahi1104a@ihcoedu.uobaghdad.edu.iq
mailto:hadi.j.m@ihcoedu.uobaghdad.edu.iq
https://orcid.org/0002-6876-7692
mailto:hadi.j.m@ihcoedu.uobaghdad.edu.iq
mailto:hadi.j.m@ihcoedu.uobaghdad.edu.iq
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https://orcid.org/0000-0000-0000-0000
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mailto:milani@umz.ac.ir


IHJPAS. 37 (1) 2024 

188 
 

process with the molecule-semiconductor plays a main role in the DSSCs operation systems. 

Quantum transfer theory indicates a greater challenge to the attention of interface contact between 

the two materials required for electron transfer in the donor-acceptor system [5–6]. Hadi et al. 

indicate that alignment energy levels and reorganization energy are the main parameters for 

electron transfer reactions in various devices [7]. Charge transfer in hetero junction materials 

occurs when electrons are transferred from the donor level to the acceptor level in the system of 

solar cell devices [8]. Furthermore, the contact region of a molecule in a semiconductor system 

has received more attention in different technological applications because the electron transfer 

reaction occurred at the cross-interface [9]. The DSSC is a photovoltaic device cell from the third 

generation; it contains a sensitized molecular dye and a photoactive electrode consisting of metal 

oxide semiconductors [10]. The N719 dye is categorized as a ruthenium metal-based organic dye, 

which includes the sensitizers for DSSCs due to their broad optical absorption spectrum [11]. The 

N749 dye is the organic attractive sensitized dye used in the DSSC solar cells; it has the chemical 

formula [(C4H9)4N]. 3[Ru(Htcterpy)(NCS)3] C69H117 N9O6RuS3, Tris [N,N,N-tributyl-1-

butanaminium] {[2,2′′6′,2′′-terpyridine] -4,4′,4′′-tricarboxylato (3-)-N1,N1′,N1′′}tris (thiocyanato-

N)hydrogen ruthenated [12]. The N749 ruthenium dye is the main sensitizer because of its 

advantages of thermal and chemical stability, good absorption of light, and more interested 

optoelectronic and electronic properties [13]. Its structure is shown in Figure 1 [14]. Currently, 

the TiO2 semiconductor is extensively used as a donor electrode in solar cells due to its high 

chemical stability and wide bandgap [15]. The mobility of electrons in electrodes relates to the 

strength of the coupling coefficient, and electrons will travel a distance from the donor to reach 

conduction oxide before  the charge recombination [16]. 

  

 

 

Figure 1. Structure of N749 sensitised dye [14]. 

Recently, the improvement of the performance of the solar cell by efficiency of DSSCs has 

increased to be reached more than 15%, it achieves with more extensive and low-cost ,it makes a 

crucial case for energy applications [17]. In this work, we extend a quantum donor-acceptor model 

based on the electron transfer theory with density-dependent transfer and strength coupling 

constants to calculate the current density and efficiency of N749 contact with titanium 

dioxide TiO2 semiconductors in heterojunction solar cell devices. 

 



IHJPAS. 37 (1) 2024 

189 
 

 

2. Theory  

The efficiency of DSSCs is defined as the ratio of output power to its incident light power density, 

as written by [18]. 

𝜂 =
𝐽𝑆𝑐𝑉𝑜𝑐.𝐹𝐹

𝐽𝑜
× 100%                                          (1) 

where 𝐽𝑜is incident light intensity(100
mW

Cm2
)and FF is the fill factor and gives ratio [19].  

𝐹𝐹 =
𝐽𝑚𝑉𝑚

𝐽𝑆𝑐𝑉𝑜𝑐
                                                             (2) 

Where 𝐽𝑚 is the average of current density in open-circuit, 𝑉𝑚 is the voltage in open-circuit, 𝐽𝑆𝑐   is 

short-circuit current density, and Voc is open circuit voltages. The current density in solar cell 

devices is given by [20]. 

𝐼 = 𝑒𝑇(𝐸) ∑[𝐹(𝐸𝐷) − 𝐹(𝐸𝐴)]                              (3) 

Where 𝑒 is electronic charge, 𝐹(𝐸𝐷)  and 𝐹(𝐸𝐴) are the Fermi distribution in donor and acceptor, 

𝑇(𝐸) is the probability transmission coefficient. It is given by   

𝑇(𝐸) =
2𝜋

ħ
 |〈𝐶𝑆𝐶𝐸𝑇〉|2𝜌𝑒𝑓𝑓(𝐸)                                (4) 

Where, 𝐶𝑆𝐶𝐸𝑇 is the strength coupling of electron transfer and 𝜌𝑒𝑓𝑓(𝐸) is the effective density in 

the system written as [21].  

𝜌𝑒𝑓𝑓(𝐸) = 𝜌𝑆𝑙𝑒𝑓𝑓/ (
6

𝜋
)

1
3⁄                                        (5)        

Where 𝜌𝑆 is electronic density in semiconductors and  𝑙𝑒𝑓𝑓 is effective length .The electronic 

density in semiconductor is given by [22].  

𝜌𝑆 = 𝜌𝐵(𝐸)〈�̂�〉𝑑𝑆

−2
3⁄
                                                  (6) 

Where 𝜌𝐵(𝐸) is the density of state of the Black dye system, 𝑑𝑠 is the atomic density of 

semiconductors and 〈�̂�〉 is the density of state in system and given by:  

〈�̂�〉 =
𝑒

−
( ℷ𝑆

𝐵+∆𝑢0)2

4ℷ𝑆
𝐵𝑘𝐵𝑇

√4𝜋ℷ𝑆
𝐵𝑘𝐵𝑇

                                                        (7) 

Here, ℷ𝑆
𝐵 and ∆𝑢0 are transition energy and the driving free energy as functions of conduction 

band energy 𝐸𝑐 and optical bandgaps Eg of N749( ∆𝑢0 = 𝐸𝑐 − 𝐸𝑔). The transition energy ℷ𝑆
𝐵 (eV) 

in equilibrium is [23].  

ℷ𝑆
𝐵(𝑒𝑉) =

𝑒2

8𝜋𝜀°
[

1

𝐷
[

1

𝑛2 −
1

𝜀
] −

1

2𝑅
[ 

𝑛𝑆𝑒𝑚
2 −𝑛2

𝑛𝑆𝑒𝑚
2 +𝑛2

1

𝑛2 −
𝜀𝑆𝑒𝑚

2 −𝜀2

𝜀𝑆𝑒𝑚
2 +𝜀2

1

𝜀2]]    (8) 



IHJPAS. 37 (1) 2024 

190 
 

 Where, 𝜀° is permittivity, D and  𝑅 = 𝐷𝑁749 + 𝐷𝑇𝑖𝑂2
 are the radius of the molecule and the 

distance between the molecule and semiconductor, 𝑛 and 𝜀 are the refractive index and dielectric 

constant of the solvent, 𝑛𝑆𝑒 is the refractive index of semiconductor and ε𝑆𝑒 is the dielectric 

constant of semiconductor. The radius is [24].  

𝐷 = (
3

4𝜋

𝑀

𝑁𝜌
)

1

3                                                                         (9)     

Where molecular weight M, Avogadro number N, and the density of the material is ρ. 

Inserting Eqs. (7), (6) and (5) in Eq.(4) to give  

𝑇(𝐸) =
2𝜋

ħ
 

𝜌𝐵(𝐸)

√4𝜋ℷ𝑆
𝐵𝑘𝐵𝑇

|〈𝐶𝑆𝐶𝐸𝑇〉|2𝑒
−

( ℷ𝑆
𝐵+∆𝑢0)2

4ℷ𝑆
𝐵𝑘𝐵𝑇 𝑙𝑒𝑓𝑓

 (
6

𝜋
)

1
3⁄

𝑑𝑆

−2
3⁄
      (10) 

Inserting the Eq. (10) in Eq. (3) with 𝐹(𝐸) = [𝐹(𝐸𝐷) − 𝐹(𝐸𝐴)] to result 

𝐼(𝐸) =
2𝜋𝑒

ħ

1)

√4𝜋ℷ𝑆
𝐵𝑘𝐵𝑇

 |〈𝐶𝐶𝐸𝑇〉|2𝑒
−

( ℷ𝑆
𝐵+∆𝑢0)2

4ℷ𝑆
𝐵𝑘𝐵𝑇 𝑙𝑒𝑓𝑓

 (
6

𝜋
)

1
3⁄

𝑑𝑆

−2
3⁄

∫ 𝜌𝐵(𝐸)𝐹(𝐸)
𝐸

0
𝑑𝐸   (11) 

The solution integral in Eq. (11) is given [25].  

∫ 𝐹(𝐸)𝜌𝐵(𝐸)
𝐸

0
𝑑𝐸 =  𝑛𝑠                                                            (12) 

Where  𝑛𝑠 is the electronic concentration at the surface semiconductor’s in unit (states cm-3). The 

Eq. (12) substituting in Eq. (11) to yield:  

𝐼(𝐸) =
2𝜋𝑒

ħ

1

√4𝜋ℷ𝑆
𝐵𝑘𝐵𝑇

 |〈𝐶𝑆𝐶𝐸𝑇〉|2𝑒
−

( ℷ𝑆
𝐵+∆𝑢0)2

4ℷ𝑆
𝐵𝑘𝐵𝑇 𝑙𝑒𝑓𝑓

 (
6

𝜋
)

1
3⁄

𝑑𝑆

−2
3⁄

𝑛𝑠           (13) 

The atomic density 𝑑𝑆 calculates due to relation [25]. 

𝑑𝑆 =
𝐷𝑆

𝐷𝑛
                                                                                         (14) 

Where 𝐷𝑛 is the number of states per atom per eV in the semiconductor and 𝐷𝑆 is the density of 

states for the semiconductor as a function of carrier concentration 𝑁𝑒, at the Fermi level and the 

Fermi energy, 𝐸𝐹, and given by [25] . 

𝐷𝑆 =
3

2
(

𝑁𝑒

𝐸𝐹
)                                                                                 (15) 

3. Results  

A combination of the quantum picture of the donor-acceptor model and electron transfer theory 

was applied to scrutinize and calculate the current density cross-interface of N749 contact with 

TiO2 based DSSCs. Due to calculate the current density produces in N749-TiO2 solar cell, it can 

be calculated the transition energy as a function of radius of N749 and TiO2, dielectric and 

refractive index of solvent and TiO2 by using Eq. (8). The radii of N749 dye and TiO2 estimate 

using Eq.(9) by inserting molecular weight M=1364.98 g/mol [26] and M=79.866 g/mol [27] and 

density 𝜌 = 1.28 
g

cm3
[26]) and  𝜌 = 4.23

g

cm3
[27] for N749 and  TiO2, respectively, results are   

7.472 𝐴0and 1.956 𝐴0for N749 and TiO2.  



IHJPAS. 37 (1) 2024 

191 
 

The transition energy was calculated onto the N749-TiO2 system with pure Dichloromethane 

solvent used in DSSCs by inserting refractive 2.609 and dielectric constant 55 of TiO2 

semiconductor [27] and refractive 1.4241 with dielectric constant of Dichloromethane (DCM) 

solvent  8.93 [28] in Eq.(8) with results ℷ𝑆
𝐵 = 0.27  𝑒𝑉 Next, the atomic density is calculated using 

Eq.(14) and (15) by taking The carrier concentration 𝑁𝑒 = 1.4 × 10141/𝑐𝑚3[29], Fermi 

energy 𝐸𝐹 = 4.52𝑒𝑉 [30], and take effective density of states 𝐷𝑛 = 8 (states /eV) of TiO2 [31] to 

result  𝑑𝑇𝑖𝑂2 = 5.80 × 1012 1

𝐶𝑚3 
. The electronic current produces from N749-TiO2 with DCM 

solvent calculates using Eq. (13) with inserting the strength coupling  

 |〈𝐶𝐶𝐸𝑇〉|2=0.1.0.2,0.3,0.4,0.5,0.6,0.7, 0.8, 0.9, 1,1.1and 1.5 x10−2 |eV|2, ℷ𝑆
𝐵 = 0.27  𝑒𝑉, effective 

length  𝑙𝑒𝑓𝑓 = 3 × 10−10𝑚[32], atomic density 𝑑𝑇𝑖𝑂2
= 5.80 × 1012 1

𝐶𝑚3 
 and concentration 𝑛𝑠 =

(3.5,4.5) × 1018 1

𝐶𝑚3 
 [31] and ∆𝑢0 = 3.4 − 3.52 = −0.12𝑒𝑉 using MATLAP program, results 

show in the Table (1). 

 

Table 1. Results of electronic current for N749-TiO2with (DCM) solvent. 

 

Strength coupling 

 |〈𝑪𝑪𝑬𝑻〉|𝟐x10−2 (𝐞𝐕/ 𝐬𝐭𝐚𝐭𝐞)𝟐 

 

The electronic current in (A) 

The electronic concentration𝑛𝑠 (
1

𝐶𝑚3  
) 

3.5 × 1018 4.5 × 1018 

0.1 6.0412E-04 7.7673E-04 

0.2 1.2082E-03 1.5535E-03 

0.3 1.8124E-03 2.3302E-03 

0.4 2.4165E-03 3.1069E-03 

0.5 3.0206E-03 3.8837E-03 

0.6 3.6247E-03 4.6604E-03 

0.7 4.2289E-03 5.4371E-03 

0.8 4.8330E-03 6.2138E-03 

0.9 5.4371E-03 6.9906E-03 

1 6.0412E-03 7.7673E-03 

1.1 6.6454E-03 8.5440E-03 

1.2 7.2495E-03 9.3208E-03 

1.3 7.8536E-03 1.0097E-02 

1.4 8.4577E-03 1.0874E-02 

1.5 9.0619E-03 1.1651E-02 

 

The probed current density 𝐽𝑚 =
𝐼

𝐴
 was calculated by the current relative to the area A of the cell 

(0.158 cm2) [34] ,results list in Table (2).   

 

 

 

 

 

 

 



IHJPAS. 37 (1) 2024 

192 
 

 

Table  2. The current density calculated for N749-TiO2 with DCM solvent. 

 

 

Strength coupling 

 |〈𝑪𝑪𝑬𝑻〉|𝟐x10−2 (𝐞𝐕/

 𝐬𝐭𝐚𝐭𝐞)𝟐 

 

Current density (A.cm-2) 

The electronic concentration( cm-3) 

3.5 × 1018 4.5 × 1018 

0.1 3.8236E-03 4.9160E-03 

0.2 7.6471E-03 9.8320E-03 

0.3 1.1471E-02 1.4748E-02 

0.4 1.5294E-02 1.9664E-02 

0.5 1.9118E-02 2.4580E-02 

0.6 2.2941E-02 2.9496E-02 

0.7 2.6765E-02 3.4412E-02 

0.8 3.0589E-02 3.9328E-02 

0.9 3.4412E-02 4.4244E-02 

1 3.8236E-02 4.9160E-02 

1.1 4.2059E-02 5.4076E-02 

1.2 4.5883E-02 5.8992E-02 

1.3 4.9706E-02 6.3908E-02 

1.4 5.3530E-02 6.8824E-02 

1.5 5.7354E-02 7.3740E-02 

The characteristic of current density J(mAcm2) verses  voltage in  Volt is shown in Table (3) 

Table 3. The J -V characteristic of N749-TiO2 devices 

 The electronic concentration 

𝟑. 𝟓 × 𝟏𝟎𝟏𝟖)1/cm3) 4.5 × 1018)1/cm3) 

V(Volt) Current)A/cm2) V(Volt) Current)A/cm2) 

0.834 0 0.857 0 

0.8 3.8236E-03 0.8 4.9160E-03 

0.75 7.6471E-03 0.75 9.8320E-03 

0.7 1.1471E-02 0.7 1.4748E-02 

0.65 1.5294E-02 0.65 1.9664E-02 

0.6 1.9118E-02 0.6 2.4580E-02 

0.55 2.2941E-02 0.55 2.9496E-02 

0.5 2.6765E-02 0.5 3.4412E-02 

0.45 3.0589E-02 0.45 3.9328E-02 

0.4 3.4412E-02 0.4 4.4244E-02 

0.35 3.8236E-02 0.35 4.9160E-02 

0.3 4.2059E-02 0.3 5.4076E-02 

0.25 4.5883E-02 0.25 5.8992E-02 

0.2 4.9706E-02 0.2 6.3908E-02 

0.15 5.3530E-02 0.15 6.8824E-02 

0.1 5.7354E-02 0.1 7.3740E-02 

0 6.054 E-02 0 7.878 E-02 

 

The characteristic of J−V curves of N749 dye-contact with TiO2 solar cell devices using two 

concentrations 3.5 × 1018 )1/Cm3)and 4.5 × 1018 )1/Cm3) are shown in Figure 2. 



IHJPAS. 37 (1) 2024 

193 
 

 

 

 

 

 

 

 

 

 

(A)                                                                  (B) 

Figure 2. The current density versus voltage under concentration 3.5 × 1018)1/cm3) and 4.5 × 1018 )1/cm3)  of the 

same devices. 

The fill factor and efficiency evaluate by using Eq. (2) and Eq. (1), respectively, with the data in 

Table (3) and Figure 2, and the results are shown in Table (4) for N749- TiO2 devices 

Table 4. The photovoltaic parameters calculated for the N749-TiO2DSSCs sensitized 

 

4.Discussion  
We looked at how well N749 black dye-in solar cells work with a dichloromethane (DCM) solvent 

and a TiO2 photoanode. We used two different electron concentrations in the system because we 

thought that the concentration would have a great effect on how well the cells worked with the 

same solvent. Table 1 indicates that electronic current is influenced by the strength of the electronic 

coupling and carrier concentration of the N749-TiO2 solar cell. We can find that the current 

increases upon increasing the strength of the electronic coupling from 0.1 to 1.5 eV. The 

concentration change of the electron-transfer cross-interface is related to the current density of 

N749- TiO2 devices and is equal to the product of how well they work and how many electrons 

they transfer. As seen in Table 2, the current increased alternatively with an increased 

concentration of carrier in Table 2. In contrast, the reorganization energy (eV) provided the system 

with the required energy of about 0.27 eV to yield charge injection quantum, which means the 

system needs less energy than the reconfiguration system to start the electron transfer process from 

excited levels of N749 dye to the conduction band in TiO2 semiconductor. A simple donor-

acceptor model has been established that allows for the description of the kinetics of electronic 

current through system devices. In fact, the electronic transfer behavior is limited by the potential 

at the interface, but the effective transition energy supplied by the energy to transfer due to polar 

media is a function of the dielectric constant and refractive index. The current density J increased 

Variables    The electronic concentration 

 

3.5 × 10181/𝑐𝑚3 4.5 × 10181/𝑐𝑚3 

𝐽𝑆𝑐(𝑚𝐴/𝑐𝑚2) 60.54 78.78 

𝑉𝑜𝑐     Volt 0.864 0.867 

𝐽𝑚(𝑚𝐴/𝑐𝑚2) 9.545 13.57  

𝑉𝑚    Volt 0.7324  0.735 

F.F 0.134 0.146  

efficiency 6.990  9.974 



IHJPAS. 37 (1) 2024 

194 
 

when the concentration increased for all strength couplings in Table 2.A larger efficiency of solar 

cells is indeed expected when the carrier concentration of the system increases. The current-

voltage characteristic, in turn, was what determined the efficiency. Also, the current density is 

affected by the transition energy and the strength of the coupling of electrons; as the strength of 

the coupling increases, so does the current density in devices that use solvent media. The decreases 

in transition energy indicated decreased potential at the interface and increases in electron transfer 

for large photocurrents. Upon excitation of the N749 dye, the current density of N749- TiO2 is 

large at 4.5 compared with 3.5, which indicates an increase in electrons through the interface of 

the N749-TiO2 device with DCM solvents. 

Another important parameter affecting the performance of solar cells is the strength of the 

coupling. Furthermore, the significant role of the increased current density as a result of increasing 

the strength of the coupling of charge transfer and recombination was assessed by reorganization 

energy with both concentrations of N749/TiO2 working in a DCM solvent medium, where the 

oxidation-reduction reaction between N749dye- and TiO2 is used as an index to explain the charge 

transfer effect of the solar cell system. As can be seen, the currents were calculated in units 

(𝑚𝐴/𝑐𝑚2) in Table (4) to estimate the efficiency, the current versus voltage is listed in Table 3 

and Figure 2. From the data in Table 4, the average open-circuit photovoltage  𝑉𝑚(Volt) and 

current 𝐽𝑚(
𝑚𝐴

𝑐𝑚2) are estimated from Figure 2 and formulated in Table 4. The performance of solar 

cells affects the strength of electronic coupling, and increasing the strength of electronic coupling 

plays a significant role in the increased current density. The recombination process is assessed by 

transition energy, strength of electronic coupling, and the carrier concentration of N749/ TiO2 

operation in the DCM media. Data results reported in Figures 2A and 2B show that in pure DCM 

solvent, the average open-circuit photovoltage Vm(Volt) and current Jm (
𝑚𝐴

𝑐𝑚2) estimated from 

Figure 2 are listed in Table 4. The efficiency of the N749-TiO2 calculated increased with carrier 

concentration increases, and the two curves closely matched the behaviour observed. To study the 

influence of carrier concentration during the optimization process, we take two values of carrier 

concentration in the cells 3.5 × 1018 1/𝑐𝑚3 and 4.5 × 1018 1/𝑐𝑚3, respectively, keep the 

distance between the N749 and TiO2 constant with the DCM solvent. It is clear that Eq. (1) 

indicates that efficiency is proportional to current density, and efficiency increases with an increase 

in current density and vice versa. As can be seen, the efficiency increased from 6.990 to 9.974 for 

the N749-TiO2 sensitised DSSCs. The increase in the concentration of electrons leads to an 

increase in current and efficiency. Table 4 shows the increases in efficiency with increasing 

concentration from 3.5 × 1018 1/𝐶𝑚3to 4.5 × 1018 1/𝐶𝑚3with transition energy for the 

N749/TiO2 system. The influence of electronic current is limited to the fill factor, efficiency and 

characteristic of the cell. Moreover, the concentration and strength of electronic coupling were 

influenced by Voc, Jsc, FF, and efficiency, as summarized in Table 4. The peak of both the current 

density and voltage difference of the solar cell indicates of the electronic recombination at a given 

concentration value. As shown in table 4, in the solar cell of concentration 3.5 × 10181/𝐶𝑚3, the 

peak-to-peak voltage and current density differences in the solar cell of concentration 4.5 ×

10181/𝐶𝑚3  are 0.003 V and 18.24 
𝑚𝐴

𝑐𝑚2, respectively.  

From the data in Table 3, the average current and open-circuit photo voltage (Voc) are estimated 

and formulated in Table 4. However, the fact that the voltage difference and peak current density 

both rise as the carrier concentration does suggests that there is more charge recombination, which 

makes the solar cell more efficient. The parameters of photovoltaic in Table 4 show that Voc, Jsc, 



IHJPAS. 37 (1) 2024 

195 
 

and efficiency increase with increasing the concentration of electrons, and decreasing the F.F 

further results in an increase in overall solar cell performance. These results are in agreement with 

the experimental results of I-V characteristic behavior in ref. [34]. 

5. Conclusion  

 In summary, a simple donor-acceptor model has been used to study and evaluate the current 

density, fill factor, and efficiency of a heterojunction N749-TiO2 device with DCM solvent for its 

potential in photovoltaic solar cell applications. The current density and efficiency in N749-TiO2 

devices are largely influenced by the carrier concentration and strength of the electronic coupling 

at limited transition energy. The efficiency was significantly enhanced from 6.990 to 9.974. The 

corresponding enhancement in efficiency can be attributed to the increased electron concentration 

in a system with limited transition energy, leading to an increase in electron transfer cross in N749-

TiO2 heterojunction devices, which in turn enhanced the I-V characteristic, fill factor, and 

efficiency of the solar cell. 

Acknowledgement  

I extend my thanks to the College of Education for pure science Ibn Al-Haitham, University of 

Baghdad for providing assistance to complete this work by opening private laboratories and 

providing scientific facilities by the staff of the Physics Department to help support the research 

project. 

 

Conflict of Interest 

The authors declare that they have no conflicts of interest. 

Funding: None. 

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