Effect of zinc doping and temperature on the properties of sprayed CuInS2 thin films

Copper indium disulfide (CuInS₂) is an efficient absorber material for photovoltaic and solar cell applications. The structural, optical, photoluminescence properties and electrical conductivities could be controlled and modified by suitably doping CuInS₂ thin films with dopants such as Zn, Sn, Bi, Cd, Na, N, O, P and As. In this work Zn (0.01 M) doped CuInS₂ thin films are (Cu/In=1.25) deposited on to glass substrates in the temperature range 300–400 °C. It is observed that the film growth temperature, ion ratio (Cu/In=1.25) and Zn-doping affect structural, optical, photoluminescence and electrical properties of sprayed CuInS₂ thin films. As the XRD patterns depict, Zn-doping facilitates the growth of CuInS₂ thin films along (112) preferred plane and in other characteristic planes. The EDAX results confirm the presence of Cu, In, S and Zn in the films. The optical studies show, about 90% of light transmission occurs in the IR regions; hence Zn-doped CuInS₂ can be used as an IR transmitter. The absorption coefficient (α) in the UV–visible region is found to be in the order of 10⁴–10⁵ cm⁻¹ which is the optimum value for an efficient absorber. The optical band gap energies increase with increase of temperatures (1.66–1.78 eV). SEM photographs reveal crystalline and amorphous nature of the films at various temperature ranges. Photoluminescence study shows that well defined broad Blue and Green band emissions are exhibited by Zn-doped CuInS₂ thin films. All the films present low resistivity (ρ) values and exhibit semiconducting nature. An evolution of p-type to n-type conductivity is obtained in the temperature range 325–350 °C. Hence, Zn species can be used as a donor and acceptor impurity in CuInS₂ thin films to fabricate efficient solar cells, photovoltaic devices and good IR Transmitters.     

Influence of annealing temperature on the phase composition and optical properties of CuInS2 films

We studied the growth of CuInS₂ thin films by single-source evaporation of CuInS₂ powder in a high-vacuum system with a base pressure of 10^?3 Pa. After evaporation, the films were annealed in a sulfur atmosphere at temperatures from 200 to 500 °C for 1 h. XRD curves and Raman spectra of the films demonstrated that chalcopyrite CuInS₂ was the major crystalline phase. The morphology of Cu_xS exhibited a star-like structure, which we report for the first time. The phase composition and optical properties of our polycrystalline thin films were effectively modified by annealing in S. For films annealed at 200 and 350 °C, a secondary CuIn₁₁S₁₇ phase appeared, which may be related to solid-state reaction in the S atmosphere. This secondary CuIn₁₁S₁₇ phase has not been widely reported in previous studies. After annealing at 500 °C, only a chalcopyrite phase was detected, with bandgap energy of 1.46 eV, which is nearly identical to the optimal bandgap energy (1.5 eV) of single-crystal CuInS₂. This indicates that the composition of the CuInS₂ film annealed at 500 °C was nearly stoichiometric. The bandgap of the samples first increased and then decreased with increasing annealing temperature, which may be attributed to an increase in grain size, the secondary CuIn₁₁S₁₇ phase, and deviation from stoichiometry.     

Size-dependent polymer/CuInS2 solar cells with tunable synthesis of CuInS2 quantum dots

This paper reports the size-dependent performance in polymer/CuInS₂ solar cells with tunable synthesis of chalcopyrite CuInS₂ quantum dots (QDs) by the solvothermal method. The CuInS₂ QDs of 3.2–5.4 nm in size are fine tuned by the reaction time in the solvothermal process with the slow supply of In³⁺ ions during the crystallization, and the band gaps increased with QDs sizes decreasing according to the results from the characterization of sizes, morphologies, component elements, valence states and band gaps of CuInS₂ QDs. We fabricated MEH-PPV/CuInS₂ solar cells, and the photoactive layer of device displayed size-dependent light-harvesting, charge separation and transport ability. Moreover, the solar cells exhibit size-dependent short circuit current (J_sc) and open circuit voltage (V_oc), with higher performance in both J_sc and V_oc for smaller CuInS₂ QDs, resulting in the maximum power conversion efficiency of ca. 0.12% under the monochromic illumination at 470 nm; CuInS₂ QDs actually serve as an effective electron acceptor material for the MEH-PPV/CuInS₂ solar cells with the wide spectral response extending from 300 to 900 nm.     

Influence of the indium nominal concentration in the formation of CuInS2 films grown by CBD

Copper indium disulfide (CuInS₂) thin films were prepared by chemical bath deposition in an acid medium on glass substrates. CuInS₂ films were grown using CuSO₄, InCl₃ and C₂H₅NS as copper, indium and sulfur sources, respectively. The CuSO₄ and C₂H₅NS concentrations remained constant, while the InCl₃ concentration was varied from 0.002 M to 0.025 M. The structural analysis show that initially the films have a mixture of CuS and CuInS₂ phases, when the indium nominal concentration increases the formation of CuInS₂ ternary compound was promoted until the final formation of a CuInS₂ film. The morphological study shows that the surface of CuInS₂ films is constituted by nanotubes. The structural and compositional analysis show that for 0.025 M InCl₃ concentration CuInS₂ films were obtained.     

Studies in CuInS2 based solar cells,including ZnS and In2S3 buffer layers

The influence of the growth conditions on the surface chemistry and on the homogeneity of the chemical composition of CuInS₂ (CIS) thin films, prepared by sequential evaporation of metallic precursors in presence of elemental sulfur in a two-stage process, was studied by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). It was found that the growth temperature affects the phase in which this compound grows. The samples deposited at temperatures around 500 °C (2nd stage) contain mainly the CuInS₂ phase; however, secondary phases like In₂S₃, Cu₂S were additionally identified at the surface and in the bulk of CuInS₂ samples deposited at temperatures greater than 550 °C. Also, the elemental composition of the layers constituting the Glass/Mo/CuInS₂/buffer/ZnO structure was studied through Auger electron spectroscopy (AES) depth profile measurements. AES measurements carried out across the Glass/Mo/CuInS₂/buffer/ZnO heterojunction gave evidence of Cu diffusion from the CuInS₂ layer towards the rest of the layers constituting the device, and of the formation of a MoS₂ layer in the Mo/CuInS₂ interface. The performance of CuInS₂-based solar cells fabricated using CBD (chemical bath deposition) deposited ZnS as buffer layer was compared to that of cells fabricated using CBD deposited In₂S₃ as buffer.     

Phase equilibrium of a CuInSe2–CuInS2 pseudobinary system studied by combined first-principles calculations and cluster expansion Monte Carlo simulations

We report the phase diagram of a CuInSe₂–CuInS₂ pseudobinary system calculated by a combination of first-principles calculations based on density functional theory, cluster expansion, and Monte Carlo simulations. All formation energies of CuIn(Se_1−xS_x)₂ (CISS) alloys are positive, indicating that CISS alloy is a miscibility gap system and has a tendency to phase separation. The phase diagram computed with conventional cluster expansion shows a miscibility gap with consolute temperature T_C=170 K. The contribution of lattice vibrations lowers T_C to 130 K. The miscibility gaps for the CuInSe₂–CuInS₂ system are predicted to be asymmetric. The effect of lattice vibrations on the miscibility gap is found to be large, and the size mismatch mechanism can be used to explain the large vibrational effect in the CuInSe₂–CuInS₂ system.     

Pulse electrodeposited copper indium sulfide films

Copper indium sulfide (CISu) films were deposited by the pulse galvanostatic deposition technique at different duty cycles. The films are polycrystalline with peaks corresponding to the chalcopyrite phase of CISu. The grain size and surface roughness increased from 10 to 25 nm and 0.85 to 2.50 nm respectively with increase of duty cycle. Optical band gap in the range of 1.30–1.51 eV was observed for the films deposited at different duty cycles. Room temperature resistivity of the films is in the range of 0.1–3.67 Ω cm. Photoconductivity measurements were made at room temperature. Photocurrent spectra exhibited maximum corresponding to the band gap of copper indium sulphide. CdS/CuInS₂ fabricated with CISu films deposited at 50% duty cycle have exhibited a V_oc of 0.62 V, J_sc of 16.30 mA cm^?2, FF of 0.71 and efficiency of 7.16%.     

Effects of Cu/In ratio and annealing temperature on physical properties of dip-coated CuInS2 thin films

CuInS₂ thin films were prepared by sol–gel dip-coating method on glass substrates using 0.75, 1 and 1.25 ratios of Cu/In in the solution. The prepared films were annealed at 380 °C, 420 °C and 460 °C for 30 min under argon environment. The structural, optical, morphological and composition properties of those were investigated by X-ray diffraction (XRD), UV–vis transmittance spectroscopy and scanning electron microscopy with an energy dispersive X-ray spectrometer. The XRD results showed that the films exhibit polycrystalline tetragonal CuInS₂ phase with (112) orientation. According to the EDX results the Cu/In ratios of the films were respectively 0.65, 0.92 and 1.35 for the Cu/In ratios of 0.75, 1 and 1.25 in the solutions. The optical band gap was found to be between 1.30 eV and 1.43 eV, depending on Cu/In ratio.     

Pulse electrodeposited copper indium sulpho selenide films and their properties

Copper indium sulpho selenide films of different composition were deposited by the pulse plating technique at 50% duty cycle (15 s ON and 15 s OFF). X-ray diffraction studies indicated the formation of single phase chalcopyrite copper indium sulpho selenide films. Transmission Electron Microscope studies indicated that the grain size increased from 10 nm–40 nm as the selenium content increased. The band gap of the films was in the range of 0.95 eV–1.44 eV. Room temperature resistivity of the films is in the range of 16.0 Ω cm–33.0 Ω cm. Films of different composition used in photoelectrochemical cells have exhibited photo output. Films of composition, CuInS_0.9Se_0.1 have exhibited maximum output, a V_OC of 0.74 V, J_SC of 18.50 mA cm^?2, ff of 0.75 and efficiency of 11.40% for 60 mW cm^?2 illumination.     

The effect of annealing on the physical properties of thermally evaporated CuIn2n+1S3n+2 thin films (n=0, 1, 2 and 3)

In this study, the annealing effect on structural, electrical and optical properties of CuIn_2n+1S_3n+2 thin films (n=0, 1, 2 and 3) are investigated. CuIn_2n+1S_3n+2 films were elaborated by vacuum thermal evaporation and annealed at 150 and 250 °C during 2 h in air atmosphere. XRD data analysis shows that CuInS₂ and CuIn₃S₅ (n=0 and 1) crystallize in the chalcopyrite structure according to a preferential direction (112), CuIn₅S₈ and CuIn₇S₁₁ (n=2 and 3) crystallize in the cubic spinel structure with a preferential direction (311). The optical characterization allowed us to determine the optical constants (refractive indexes 2.2–3.1, optical thicknesses 250–500 nm, coefficients of absorption 10⁵ cm^?1, coefficients of extinction <1, and the values of the optical transitions 1.80–2.22 eV) of the samples of all materials. We exploited the models of Cauchy, Wemple–DiDomenico and Spitzer–Fan for the analysis of the dispersion of the refractive index and the determination of the optical and dielectric constants.     

All-conjugated diblock copolymer of poly(3-hexylthiophene)-block-poly(3-phenoxymethylthiophene) for field-effect transistor and photovoltaic applications

The electronic properties, morphology and optoelectronic device characteristics of conjugated diblock copolythiophene, poly(3-hexylthiophene)-block -poly(3-phenoxymethylthiophene) (P3HT-b-P3PT), are firstly reported. The polymer properties and structures were explored through different solvent mixtures of chloroform (CHCl₃), dichlorobenzene (DCB), and CHCl₃:DCB (1:1 ratio). The absorption maximum (λ_max) of P3HT-b-P3PT prepared from DCB was around 554 nm with a shoulder peak indicative for the highly crystalline structure around 604 nm while that from CHCl₃ was 516 nm without the clear shoulder peak. The field-effect hole mobility of P3HT-b-P3PT increased from ～6.0 × 10^?3, ～8.0 × 10^?3 to ～2.0 × 10^?2 cm² V^?1 s^?1 as the DCB content in the solvent mixture enhanced. The AFM images suggested that the highly volatile CHCl₃ processing solvent led to the amorphous structure, on the other hand, less volatile DCB resulted in the largely crystalline structure of the P3HT-b-P3PT. Such difference on the polymer structure and hole mobility led to the varied power conversion efficiency (PCE) of the photovoltaic cells fabricated from the blend of P3HT-b-P3PT/[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) (1:1, w/w): 1.88 (CHCl₃), 2.13 (CHCl₃:DCB (1:1)), and 2.60% (DCB). The PCBM blend ratio also significantly affected the surface structure and the solar cell performance. The PCE of polymer/PCBM could be improved to 2.80% while the ratio of polymer to PCBM went to 1:0.7. The present study suggested that the surface structures and optoelectronic device characteristics of conjugated diblock copolymers could be easily manipulated by the processing solvent, the block segment characteristic, and blend composition.     

Using d-limonene as the non-aromatic and non-chlorinated solvent for the fabrications of high performance polymer light-emitting diodes and field-effect transistors

Aiming to environment protection, green solvents are crucial for commercialization of solution-processed optoelectronic devices. In this work, d-limonene, a natural product, was introduced as the non-aromatic and non-chlorinated solvent for processing of polymer light-emitting diodes (PLEDs) and organic field effect transistors (OFETs). It was found that d-limonene could be a good solvent for a blue-emitting polyfluorene-based random copolymer for PLEDs and an alternating copolymer FBT-Th₄(1,4) with high hole mobility (μ_h) for OFETs. In comparisons to routine solvent-casted films of the two conjugated polymers, the resulting d-limonene-deposited films could show comparable film qualities, based on UV–vis absorption spectra and observations by atomic force microscopy (AFM). With d-limonene as the processing solvent, efficient blue PLEDs with CIE coordinates of (0.16, 0.16), maximum external quantum efficiency of 3.57%, and luminous efficiency of 3.66 cd/A, and OFETs with outstanding μ_h of 1.06 cm² (V s)⁻¹ were demonstrated. Our results suggest that d-limonene would be a promising non-aromatic and non-chlorinated solvent for solution processing of conjugated polymers and molecules for optoelectronic device applications.     

Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.     

First-principles investigation of the optical properties of CuIn(SxSe1–x)2

We optimized the lattice structure of sulfur-doped CuInSe₂ using first principles. The lattice constants for CuIn(S_xSe_1–x)₂ vary linearly with x according to a(x)=–0.02828x+0.58786 nm and c(x)=–0.05692x+1.1834 nm, which agree well with experimental data. The optical properties of CuIn(S_xSe_1–x)₂ were then systematically investigated using first-principles calculations with the HSE06 functional. We present data for the complex dielectric function, refractive index, extinction coefficient, reflectivity index, absorption coefficient, and optical bandgap for CuIn(S_xSe_1–x)₂. The optical bandgap E_g obtained from the absorption coefficient is 1.07 eV for CuInSe₂ and 1.384 eV for CuInS₂. These values are very close to experimental results, indicating that first-principles calculations can yield accurate bandgap values. The optical bandgap of CuIn(S_xSe_1–x)₂ increases linearly with the sulfur concentration according to E_g=0.3139x+1.0825 eV.     

Efficient solution processed D1-A-D2-A-D1 small molecules bulk heterojunction solar cells based on alkoxy triphenylamine and benzo[1,2-b:4,5-b′]thiophene units

Two molecules denoted as VC96 and VC97 have been synthesized for efficient (η = 6.13% @ 100 mW/cm² sun-simulated light) small molecule solution processed organic solar cells. These molecules have been designed with the D₁-A-D₂-A-D₁ structure bearing different central donor unit, same benzothiadiazole (BT) as π-acceptor and end capping triphenylamine. Moreover, the optical and electrochemical properties (both experimental and theoretical) of these molecules have been systematically investigated. The solar cells prepared from VC96:PC₇₁BM and VC97:PC₇₁BM (1:2) processed from CF (chloroform) exhibit a PCE (power conversion efficiency) of η = 4.06% (J_sc = 8.36 mA/cm², V_oc = 0.90 V and FF = 0.54) and η = 3.12% (J_sc = 6.78 mA/cm², V_oc = 0.92 V and FF = 0.50), respectively. The higher PCE of the device with VC96 as compared to VC97 is demonstrated to be due to the higher hole mobility and broader IPCE spectra. The devices based on VC96:PC₇₁BM and VC97:PC₇₁BM processed with solvent additive (3 v% DIO, 1,8-diiodooctane) showed PCE of η = 5.44% and η = 4.72%, respectively. The PCE device of optimized VC96:PC₇₁BM processed with DIO/CF (thermal annealed) has been improved up to 6.13% (J_sc = 10.72 mA/cm², V_oc = 0.88 V and FF = 0.61). The device optimization results from the improvement of the balanced charge transport and better nanoscale morphology induced by the solvent additive plus the thermal annealing.     

Defect studies in Cu2ZnSnSe4 and Cu2ZnSn(Se0.75S0.25)4 by admittance and photoluminescence spectroscopy

To achieve higher record efficiencies for solar cells containing Cu₂ZnSnSe₄ (CZTSe), Cu₂ZnSnS₄ (CZTS) or their solid solution Cu₂ZnSn(Se_xS_1?x)₄ (CZTSSe) as an absorber, it is necessary to obtain more knowledge about defect structure of these materials. In this work, admittance spectroscopy (AS) and low temperature photoluminescence spectroscopy (PL) were used for defect studies. Admittance spectroscopy in the frequency range from 20 Hz to 10 MHz was used for studies of CZTSe/CdS and CZTSSe/CdS monograin layer heterojunctions. The measurement temperature varied from 140 K to 245 K. Two defect states (labelled E_A1 and E_A2) were found in Cu₂ZnSnSe₄ and Cu₂ZnSn(Se_0.75S_0.25)₄. In different CZTSe/CdS heterojunctions the E_A2 state was present at 74 meV, but the second E_A1 defect state changed from 87 meV to 100 meV during time and had varying properties. In Cu₂ZnSn(Se_0.75S_0.25)₄ the E_A2 state was found at 25 meV. The E_A1 state at 154 meV showed the same properties as the two defect levels in CZTSe. In both cases the E_A2 defect state was attributed to an acceptor defect and the E_A1 state with changing properties to interface states. The detected PL bands were at 0.946 eV in CZTSe and at 1.028 eV in Cu₂ZnSn(Se_0.75S_0.25)₄. Obtained by PL measurements, defect states at 69 meV in CZTSe and at 39 meV in Cu₂ZnSn(Se_0.75S_0.25)₄ were attributed to the same acceptor defect that was found from the AS measurements.     

Fabrication of single crystal field-effect transistors with phenacene-type molecules and their excellent transistor characteristics

Single crystal field-effect transistors (FETs) using [6]phenacene and [7]phenacene show p-channel FET characteristics. Field-effect mobilities, μs, as high as 5.6 × 10^?1 cm² V^?1 s^?1 in a [6]phenacene single crystal FET with an SiO₂ gate dielectric and 2.3 cm² V^?1 s^?1 in a [7]phenacene single crystal FET were recorded. In these FETs, 7,7,8,8-tetracyanoquinodimethane (TCNQ) was inserted between the Au source/drain electrodes and the single crystal to reduce hole-injection barrier heights. The μ reached 3.2 cm² V^?1 s^?1 in the [7]phenacene single crystal FET with a Ta₂O₅ gate dielectric, and a low absolute threshold voltage |V_TH| (6.3 V) was observed. Insertion of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F₄TCNQ) in the interface produced very a high μ value (4.7–6.7 cm² V^?1 s^?1) in the [7]phenacene single crystal FET, indicating that F₄TCNQ was better for interface modification than TCNQ. A single crystal electric double-layer FET provided μ as high as 3.8 × 10^?1 cm² V^?1 s^?1 and |V_TH| as low as 2.3 V. These results indicate that [6]phenacene and [7]phenacene are promising materials for future practical FET devices, and in addition we suggest that such devices might also provide a research tool to investigate a material’s potential as a superconductor and a possible new way to produce the superconducting state.     

Solvent–vapor induced morphology reconstruction for efficient PCDTBT based polymer solar cells

This paper reports polymer solar cells with a 7% power conversion efficiency (PCE) based on bulk heterojunction (BHJ) composites of the alternating co-polymer, poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole) (PCDTBT), and the fullerene derivative [6,6]-phenyl C₇₁-butyric acid methyl ester (PC₇₁BM). As confirmed by transmission electron microscopy, solvent–vapor annealing (SVA) of the thin (70 nm) BHJ photoactive layer by exposure to chloroform vapor, for a short period of time (30 s) after deposition, leads to reconstructed nanoscale morphology of donor/acceptor domains, well-dispersed fullerene phase and effective photo-absorption of BHJ. Consequently, SVA-reconstructed devices with a PCDTBT:PC₇₁BM blend ratio of 1:5 (wt%) exhibit ～50% improvement in PCE, with short-circuit current J_sc = 15.65 mA/cm², open-circuit voltage V_oc = 0.87 V, and PCE = 7.03%, in comparison to those of the 1:4 (wt%) blends with SVA treatment.     

Low-voltage,high speed inkjet-printed flexible complementary polymer electronic circuits

We report the development of high-performance inkjet-printed organic field-effect transistors (OFETs) and complementary circuits using high-k polymer dielectric blends comprising poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) and poly(methyl methacrylate) (PMMA) for high-speed and low-voltage operation. Inkjet-printed p-type polymer semiconductors containing alkyl-substituted thienylenevinylene (TV) and dodecylthiophene (PC12TV12T) and n-type P(NDI2OD-T2) OFETs showed high field-effect mobilities of 0.1–0.4 cm² V^?1 s^?1 and low threshold voltages down to 5 V. These OFET properties were modified by changing the blend ratio of P(VDF-TrFE) and PMMA. The optimum blend – a 7:3 wt% mixture of P(VDF-TrFE) and PMMA – was successfully used to realize high-performance complementary inverters and ring oscillators (ROs). The complementary ROs operated at a supplied bias (V_DD) of 5 V and showed an oscillation frequency (f_osc) as high as ～80 kHz at V_DD = 30 V. Furthermore, the f_osc of the complementary ROs was significantly affected by a variety of fundamental parameters such as the electron and hole mobilities, channel width and length, capacitance of the gate dielectrics, V_DD, and the overlap capacitance in the circuit configuration.     

Effects of tetramethylene sulfone solvent additives on conductivity of PEDOT:PSS film and performance of polymer photovoltaic cells

A solvent additive in PEDOT:PSS solution is one of many methods to improve the conductivity of the poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films. We explore a new type of the solvent additive, namely tetramethylene sulfone (TMS), for the fabrication of the PEDOT:PSS conductive layer in the ITO/PEDOT:PSS/P3HT:PCBM/TiO_x/Al polymer photovoltaic cells, in comparison to a more common dimethyl sulfoxide (DMSO) solvent additive. At optimal conditions, the TMS additive at 10 wt.% has been found to enhance the conductivity of pristine PEDOT:PSS films from 0.04 S/cm up to approximately 189 S/cm, compared with the highest conductivity for the case of the DMSO additive at 15 wt.% of 117 S/cm. Possible mechanisms of this conductivity enhancement, relating to the polymer conformation and the film morphology, have been investigated by Raman spectroscopy, X-ray diffraction, atomic force microscopy, and transmission electron microscopy. The performance of the polymer photovoltaic cells fabricated with the solvent additives PEDOT:PSS films follows a similar trend to the conductivity of the films as a function of the additive concentration. The additives mainly lead to greater short circuit current density (J_sc) of the photovoltaic cells. The highest power conversion efficiency (PCE) of 2.24% of the device has been obtained with the 10 wt.% TMS additive of, compared to the PCE of 1.48% for the standard device without solvent additive.