CZTS Thin Film Solar Cells Research Articles

Study on the Optimization of Cu-Zn-Sn-O to Prepare Cu2ZnSnS4 Thin Film via a Nano Ink Coating Method.

To reduce the formation of the impurity phase, a buffer volume can be used to expands and smooths the surface of Cu2ZnSnS4(CZTS) thin film. In this study, a Cu-Zn-Sn-O(CZTO) precursor was synthesized through the process of coprecipitation-calcination-ball milling-spin coating. The influence of pH, temperature, and PVP on the constituent of hydroxides was investigated in the process of coprecipitation. Cu-Zn-Sn-O with appropriate compositions could be obtained by regulating the temperature and preservation time of the calcination stage. After ball milling to form a nano ink, and then spin coating, SEM images proved the generation of CZTO precursors, which effectively promoted the formation of Cu2ZnSnS4 thin films. Finally, the phase, microstructure, chemical composition, and optical properties of the Cu2ZnSnS4 thin films prepared by sulfurized annealing CZTO precursors were characterized by EDX, XRD, Raman, FESEM, Hall effect, and UV methods. The prepared CZTS thin film demonstrated a band gap of 1.30 eV, which was suitable for improving the performance of CZTS thin film solar cells.

Investigation of the properties of CZTS/FTO interface

Fluorine doped tin oxide (FTO) has low lattice mismatch with Cu2ZnSnS4 (CZTS) thin film and has been considered as a suitable substrate material for CZTS. The interface properties between CZTS and FTO play an important role in the photovoltaic performance of CZTS thin film solar cells. However, studies on the properties of the CZTS/FTO interface are scarce. In this work, the phase structures, compositions, morphologies, and electrical contact properties of the CZTS/FTO interfaces were investigated. CZTS thin films with annealing temperature from 500 °C to 580 °C were deposited on FTO-coated glass substrate by sol-gel, spin-coating, and annealing processes. The CZTS/FTO interfaces were characterized by X-ray diffraction, Raman spectroscopy, energy-dispersive spectroscopy, secondary ion mass spectroscopy, scanning electron microscopy, resistivity, and current–voltage (I–V) characteristic curve measurement. The results show the successful formation of CZTS/FTO interfaces. No interfacial layer was found at all the CZTS/FTO interfaces, indicating the stability of the CZTS/FTO interface during high temperature treatment. The I–V curves of all the CZTS/FTO structures were near linear, revealing the formation of ohmic contact between CZTS and FTO. The experimental results in this work indicate the feasibility of FTO as a substrate and back electrode for CZTS thin films.

Influence of Cd0.6Zn0.4S buffer layer on the band alignment and the performance of CZTS thin film solar cells

The CdS film is one of the best candidates for the n-type buffer layer in Cu 2 ZnSnS 4 (CZTS) solar cells. However, the inappropriate band alignment at CdS/CZTS heterojunction result in the high barrier for the photogenerated carriers, which decrease the open-circuit voltage and the short-circuit current. In this paper, the crystallization and the optical bandgap of the Zn-doping Cd 0.6 Zn 0.4 S film fabricated by chemical bath deposition were studied. XRD showed that the lattice constant of hexagonal Cd 0.6 Zn 0.4 S decreased a little after Zn doping because of the shorter bond length of Zn–S. Photoluminescence and transmittance spectra showed the band gap of Cd 0.6 Zn 0.4 S thin film increased from 2.59 to 2.88 eV due to Burstein-Moss shift. The conduction band offset (CBO) obviously decreased from 0.51 eV in CZTS/CdS heterojunction to 0.27 eV in CZTS/Cd 0.6 Zn 0.4 S heterojunction which result in the short-circuit current increasing from 12.25 to 15.05 mA/cm 2 . The conversion efficiency (E ff ) and fill factor (FF) of the solar cell based on CZTS/Cd 0.6 Zn 0.4 S were increased from 2.31% to 31.06 to 4.88% and 47.45, comparing to CZTS/CdS solar cell. • The effects of the Zn-doping Cd 0.6 Zn 0.4 S film fabricate of Cu 2 ZnSnS 4 thin film solar cells were studied in detail. • To our knowledge, the (CBO) decreased from 0.51 eV in CZTS/CdS heterojunction to 0.27 eV in CZTS/Cd 0.6 Zn 0.4 S heterojunction. • The best Eff. of the fabricated CZTS/Cd 0.6 Zn 0.4 S thin film solar cell is 4.88% with the V oc of 628 mV, J sc of 15.05 mA/cm 2 .

Elucidating the Influence of Sulfur Vacancies on Nonradiative Recombination Dynamics in Cu2ZnSnS4 Solar Absorbers.

We report a time-domain ab initio simulation of charge carrier trapping and relaxation dynamics in pristine and defect-containing kesterite Cu2ZnSnS4 (CZTS) structures. Our simulations show that introduction of a neutral sulfur vacancy in the CZTS system leads to a decrease of the charge recombination rate by a factor of ∼4, and the doubly positively charged sulfur vacancy results in a minor decrease of carrier lifetime, as compared to the pristine CZTS system. The neutral sulfur vacancy weakens the nonadiabatic (NA) electron-phonon coupling by moderately localizing charge density and accelerates the pure dephasing process, extending charge carrier lifetime. Therefore, the neutral sulfur vacancy is electrically benign. The doubly positively charged sulfur vacancy introduces a subgap state which is hardly populated, and recombination of the electron and hole bypassing the trap state dominates. As a result, the recombination rate decreases in the doubly charged sulfur vacancy structure. The reported results identified the key role of the sulfur-related vacancy on charge carrier trapping and relaxation of CZTS materials, carrying important implications for further optimization of CZTS and other thin-film solar cell materials.

CZTS thin film solar cells on flexible Molybdenum foil by electrodeposition-annealing route

Earth-abundant and non-toxic Kesterite-based Cu2ZnSnS4 (CZTS) thin film solar cells are successfully fabricated on flexible Molybdenum (Mo) foil substrates by an electrodeposition-annealing route. A well-adherent, densely packed, homogeneous, compact, and mirror-like CZT precursor is initially produced through electrodeposition by using a rotating working electrode. Subsequently, the co-electrodeposited CuZnSn (CZT) precursor is sulfurized in quartz tube furnace at 550 °C for 2 h in N2 atmosphere with the presence of elemental sulfur in order to form CZTS. Different characterization techniques like XRD, SEM, HR-TEM, Raman, and Photoluminescence demonstrate that almost phase-pure CZTS formed after sulfurization. A flexible Al/Al-ZnO/i-ZnO/CdS/CZTS/Mo foil solar cell is produced, where CdS is deposited by chemical bath deposition and transparent conducting oxide (TCO) is deposited by DC sputtering. The CZTS solar device shows a 0.55% power conversion efficiency on flexible Mo foil substrate and it constitutes the first prototype of this kind of solar cell produced by electrodeposition-annealing route without any surface modification of the Mo substrate.Graphic abstract

Effect of Prefabricated Layer Structure on Properties of CZTS Thin Films and Solar Cells

Cu2ZnSnS4 (CZTS) thin films based on single-layer and double-layer prefabricated layer structure were prepared on substrates by two-step method. The influence of prefabricated layer structure on the surface morphology, element composition and photoelectric properties of CZTS thin film was studied. The crystal structure, surface morphology and composition of the films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. The experimental results showed that the CZTS thin film with double-layer prefabricated structure had larger grain size, better crystallization and uniform distribution of film components than the CZTS thin film with single-layer prefabricated structure. The conversion efficiency of CZTS solar cells based on the double-layer prefabricated structure increased from 0.25% of the single-layer prefabricated structure to 3.05%. Therefore, the double-layer prefabricated structure CZTS thin film was more suitable as the absorption layer of CZTS thin film solar cells.

The preparation of Cu2ZnSnS4 thin film solar cell based on oxygen containing precursor

In this paper, we reported a new method to fabricate Cu2ZnSnS4 (CZTS) thin film solar cells. Oxygen containing precursor thin films were deposited on the Mo-coated soda lime glass (SLG) by sputtering ZnO, SnO2 and Cu targets. For getting higher quality CZTS thin films, the effects of different annealing temperatures of 380 °C, 480 °C, 580 °C and 650 °C on CZTS films were systematically investigated. The results showed that the optimum annealing temperature was 580 °C. Through optimizing the sulfurization process, phase-pure CZTS thin films with compact and large grains were obtained. Composition analysis showed that O was not detected after sulfurizing process which indicated all of O was replaced by S. And due to the stability of SnO2, the loss of tin can be avoided. In addition, ZnO not only can provide zinc sources, but also can decrease the thickness of MoS2 as a barrier layer. Finally, CZTS solar cells based on sputtering oxides targets were obtained and the preliminary fabricated CZTS thin film solar cells had an efficiency of 5.08%, with an open-circuit voltage of 645 mV, a short-circuit current density of 21.74 mA/cm2 and a fill factor of 36.23%.

Toxic-free surface level sulphur doped 1D Ti-Ox-Sy nanorods for superstrate heterojunction CZTS thin-film solar cells

Surface level sulphur (S) doped TiO2 nanorods (S-TNRs) were fabricated via toxic-free novel three-step processes such as low-temperature hydrothermal method followed by thermal evaporation (S layer) and post-annealing (350 °C, 450 °C and 550 °C) techniques. Present work focuses on the comprehensive studies of surface level doping, structure, morphology and compositional properties of different temperature annealed S-TNRs for CZTS thin-film (Au/CZTS/S-TNRs/TNRs/FTO) solar cells. The oxidation states of incorporated S atoms in the TiO2 matrix were identified from X-ray photoelector spectroscopy (XPS) analysis. A reduction in bandgap for 350 °C annealed S-TNRs film was observed from UV-Vis spectroscopy. The electrical characteristics showed the fabricated solar cells strongly depend on the S-TNRs annealing temperature. Proposed technique would be useful in effective and controlled (surface level) doping of S atoms into any desired nanostructured metal oxides for optoelectronic applications and, further useful in fabricating cadmium (Cd) free buffer layer in chalcogenide solar cells.

Properties of thermally evaporated CZTS thin films and numerical simulation of earth abundant and non toxic CZTS/Zn(S,O) based solar cells

Earth abundant Cu2ZnSnS4 (CZTS) films were grown by thermal evaporation technique onto non heated substrates. As deposited CZTS films were annealed under two different atmospheres: (1) vaccum annealing atmosphere and (2) sulfur annealing atmosphere followed by vacuum annealing. The samples were analyzed for their microstructural, electrical and optical properties before and after annealing. X-Ray Diffraction (XRD) analysis revealed that the as deposited film was amorphous whereas the annealed ones were polycrystalline with a highly (1 1 2) orientation. Raman spectroscopy confirmed the phase purity of annealed CZTS films. Both annealing atmospheres were found to decrease the band gap energy and the resistivity of the samples. All films exhibited p-type electrical conductivity. Numerical simulation of earth abundant CZTS thin film solar cells with non toxic Zn(S,O) buffer layer was performed by Solar Cell Capacitance Simulator (SCAPS-1D) using the experimental results obtained for CZTS and Zn(S,O) films. Zn(S,O) was used to substitute toxic CdS in earth-abundant Cd-free CZTS solar cells. A maximum conversion efficiency of 12.60% was obtained for Mo/p-Cu2ZnSnS4/n-Zn(S,O)/i-ZnO/n-ZnO:Al structure with CZTS film annealed under sulfur annealing atmosphere followed by vacuum annealing.

Reduction of interface recombination current for higher performance of p+-CZTSxSe(1-x)/p-CZTS/n-CdS thin-film solar cells using Kesterite intermediate layers

There have been significant efforts to enhance the performance of CZTS thin-film solar cells. However, the increase in series resistance, formation of the unfavorable MoS2 between the absorber layer and back-contact, and recombination losses are some of the most effective factors for the low values of the efficiency and open-circuit voltage parameters. In this paper, five experimental CZTS solar cells with high efficiency of 8.4–11% have been mainly studied and discussed. Afterwards, two experimental works have been reproduced to validate our results. Additionally, with introducing the thin CZTSxSe(1-x) layer between the Mo back-contact and CZTS absorber layer, the efficiency and open-circuit voltage of solar cells have been notably improved. There is a significant decrease in recombination losses (less than 12 mA/cm2) after using CZTSxSe(1-x) intermediate layers between the absorber layer and back-contact. Using the CZTSe, and CZTS0.2Se0.8 thin layers and optimizing the structure as p+pn structure (p+-CZTSxSe(1-x)/p-CZTS/n-CdS), the following efficiencies (and open-circuit voltage) are achieved as: 15.98% (921 mV) and 17.81% (986 mV), respectively. Simulations demonstrate that at 0.8-V bias for p+-CZTS0.2Se0.8/p-CZTS/n-CdS structure, the recombination current total density is reduced to 6.47 mA/cm2. To obtain the highest performance in the proposed structures, the absorber layer carrier concentration should be 1 × 1016 cm−3 and the intermediate layer carrier concentration needs to be within the range of 1 × 1017 cm−3 to 1 × 1018 cm−3. Furthermore, the optimum thickness of CZTSe and CZTSSe intermediate layers in the proposed structures is 50 nm.

The impact of the carrier concentration and recombination current on the p+pn CZTS thin film solar cells

One of the main causes of low performance of Cu2ZnSnS4 (CZTS) based thin film solar cells is its high recombination current. In this paper, the effects of the carrier concentration and recombination current in the CZTS thin film solar cells have been carefully scrutinized. In continue, for comparison and validation, two simulated structures based on the CZTS absorber layer have been reproduced and the influence of the absorber layer defects and carrier concentration has been analyzed. In this work, two different structures using p+-CZTS intermediate layer (between the CZTS absorber layer and Mo back-contact) and dual CZTS layer have been proposed and optimized to decrease recombination and extract the desired photovoltaic parameters. By using and optimizing these structures as p+pn junction, 15.62% and 19.08% efficiencies have been achieved in p+-CZTS intermediate layer and p+pn CZTS dual layer structures, respectively. The highest efficiency of dual absorber based solar cell is achieved when the carrier concentration of the p+-CZTS and p-CZTS absorber layers is 1 × 1018 cm−3 and 5 × 1015 cm−3, respectively. Moreover, the optimum thickness of the p+-CZTS and p-CZTS absorber layers in p+pn CZTS dual layer structure is 1 and 1.5 µm, respectively. Finally, the total recombination current density is reduced to 2.05 mA/cm2.

Development of Cu2ZnSnS4 films from a non-toxic molecular precursor ink and theoretical investigation of device performance using experimental outcomes

In this paper, we reported a facile and cost effective way to deposit Cu2ZnSnS4 (CZTS) films using a non-toxic precursor ink and photovoltaic performance of single junction CZTS solar cell by implementing experimentally obtained optical and electrical parameters of our CZTS film in a simulation program known as SCAPS-1D (solar cell capacitance simulator in one dimension). The ink was deposited over glass substrates by drop casting method and the as-deposited films were subjected to thermal annealing at 450 and 500 °C in N2 atmosphere. X-ray diffraction and Raman scattering analysis revealed the polycrystalline nature of CZTS films with tetragonal kesterite phase. The values of optical band gap (Eg) were found to vary in between 1.26 and 1.41 eV depending on the annealing condition. Hall measurement showed p-type electrical conductivity with good electrical properties, yielding resistivity (ρ) in the range of 18.6–1.9 × 102 Ω-cm, carrier concentration (n) = 6.65 × 1016–8.72 × 1017 cm−3 and mobility (μ) = 10.6–19.4 cm2/Vs. Numerical simulation of CZTS thin film solar cells with CdS buffer layer was modeled through SCAPS-1D using the experimental data of CZTS films obtained in this work. A maximum efficiency of 14.12% was obtained considering all possible defects and radiative recombination which can be occurred under realistic situation.

Enhancing the open-circuit voltage and efficiency of CZTS thin-film solar cells via band-offset engineering

Limits on the conversion efficiency and open-circuit voltage lead to low kesterite thin-film solar cell performance. The conduction band offset (CBO) between the absorber and buffer layers (p-CZTS and n-CdS) is considered to be one of the effective factors for the performance of these devices. The simulation results demonstrated that the optimal thickness and doping concentration for obtaining a high performance in the solar cell which is based on CZTS/CdS absorber/buffer layers would respectively be 50 nm and 1.5 × 1017 cm−3. The CBO at absorber/buffer interface plays a significant role in solar cell performance and the highest CZTS-based solar cell efficiency is obtained within the range of − 0.4 eV and + 0.4 eV of the CBO. Solar cell performance decreases from 5.12 to about 3% when the positive CBO increases from 0.4 to 0.7 eV. Moreover, the impact of CBO on device quantum efficiency was investigated. The optical response range changed with an increase in + ΔEC and the highest value (about 80%) was observed in visible and near ultraviolet light within the range of 400–520 nm. In − ΔEC, electrons can be transferred from the buffer layer to the window layer and the optical photons proportional to the buffer layer’s band gap help generate free electrons and holes, which cause a slower reduction of the quantum efficiency within the negative offsets and the above-mentioned range, through electric field bending. In addition, a large number of n-type materials such as CdS, SnS2, ZnO, ZnTe, ZnS, Zn(O, S), (Mg, Zn)O, In2S3, TiO2, and CdTe were analyzed as buffer layers in CZTS-based thin-film solar cell. The CZTS-based thin-film solar cells with SnS2, ZnO0.55S0.45, ZnO0.80S0.20, and Mg0.2Zn0.8O led to a conversion efficiency of about 13%. Furthermore, an open-circuit voltage of above 700 mV was obtained by using ZnO0.40S0.60 and Mg0.1Zn0.9O buffer layers. By introducing the CZTSe/CZTS absorber layer and SnS2 buffer layer in the structure of the proposed solar cell, the best efficiency and open-circuit voltage is deduced as 16.28% and 780 mV, respectively.

Investigation of the photovoltaic performance of n-Zno/n-CdS/p-Cu2ZnSnS4 solar cell

The semiconducting thin film solar cell based on Cu2ZnSnS4 (CZTS) materials is considered as a promising candidate for very large-scale application due to high absorption coefficient and low cost. In this study, the performances of n-ZnO/n-CdS/p-CZTS solar cells were numerically simulated using the AFORS-HET software. The influences of double-graded bandgap and thickness of CZTS layer on the performances of the solar cell were investigated. The calculated results show that double-graded bandgap structure can greatly optimize the conversion efficiency of CZTS thin film solar cell. The optimal dual gradient structure is 1.4 eV-1.3 eV-1.5 eV, the optimal thickness ratio is 11:1, and the conversion efficiency could be 26.63%. The results of this study can serve as a guide in fabricating CZTS solar cell.

Non-uniform distribution of sulfur vapor and its influence on Cu2ZnSnS4 thin film solar cells

The morphological, compositional and structural properties of the Cu2ZnSnS4 (CZTS) thin films and the device parameters of solar cells are strongly influenced by the sulfur partial pressure during the sulfurization process. To investigate the distribution of sulfur vapors along the sulfurization chamber, the uniformity of the CZTS thin films and solar cells during sulfurization process, several same samples were sequentially placed in the chamber. The device performance of CZTS thin film solar cells shows a strong correlation with the positions in the sulfurization zone and the morphologies of the CZTS thin films. An optimal position was found in the sulfurization furnace where could improve the crystallinity of CZTS thin films, reduce the formation of secondary phases, and improve the efficiency of solar cells. The best solar cell in the optimal position shows an efficiency of 3.49%, which was restrained by the Sn loss. The possible reasons for the non-uniform distribution of sulfur vapor are analyzed.

Improving the crystallization and carrier recombination of Cu2ZnSnS4 thin film deposited on Mo-coated soda-lime glass by extra sodium doping through solution process

In this paper an easy and mild solution-processed method is introduced to prepare extra sodium (Na) doped Cu2ZnSnS4 (CZTS) films on Mo-coated soda-lime glasses. Through this method, the Na-doping concentration can be adjusted at the range from 3.9% to 5.4% continuously. By extra Na doping through solution process, the grain size of CZTS particles was enlarged apparently without introducing any impurity phase. More excitingly, the photoluminescence (PL) spectrum indicates that high Na-doping concentration has the strong suppression ability on the band-gap recombination of CZTS films. The carrier lifetime is promoted from 2.1 ns to 2.83 ns. CZTS thin film solar cell with 4.8% Na-doping concentration shows the best performance.

Influence of pre-sulfurization temperature on properties of Cu2ZnSnS4 thin film in two-step sulfurization process

In this study, Cu2ZnSnS4 (CZTS) thin films were prepared by magnetron sputtering deposition of the Cu-Zn-Sn metallic precursor (CZT) on flexible molybdenum foils and a two-step sulfurization process. Low-temperature pre-sulfurization was performed before the final high-temperature sulfurization during the two-step sulfurization process to enhance the properties of CZTS. This paper presents a method to improve the properties of CZTS thin films, making them conducive to solar cell applications. The compositions and morphologies of CZTS were confirmed using energy dispersive spectroscopy and scanning electron microscopy, respectively. X-ray diffraction was conducted to investigate the structural properties of the CZTS thin films, and the results revealed that the CZTS phase in all the samples had a preferential plane along (112). Moreover, Raman spectroscopy helped distinguish the ZnS and Cu2SnS3 phases that are close to kesterite CZTS. Compared to the thin film prepared without pre-sulfurization treatment, a suitable increase in pre-sulfurization temperature could reduce the loss of Sn and enhance the crystallinity of CZTS. However, a higher pre-sulfurization temperature could result in the formation of secondary phases. The CZTS thin films exhibited good properties when the CZT precursor was pre-sulfurized at 150 °C. In addition, the CZTS thin films had a single phase and flat and dense surfaces with large grains. The optical parameters were calculated based on the reflectance and transmittance data obtained by UV–Vis spectroscopy. The absorption coefficient was larger than 1 × 104 cm−1, and the optical bandgap was about 1.55 eV; these are suitable properties for CZTS absorption layers in CZTS thin-film solar cells.

Surface morphology control of Cu2ZnSnS4 by addition of cellulose in solution process for high performance superstrate solar cell

Hydroxypropyl cellulose is added into the precursor solution to deposit Cu2ZnSnS4 (CZTS) thin film for superstrate solar cell. The crystallinity and morphologies of CZTS thin films can be manipulated by adding a small amount of hydroxypropyl cellulose. With addition of 1.0 wt% hydroxypropyl cellulose, the crystallinity and grain size of CZTS are obviously improved, and the light-to-electric conversion efficiency of CZTS thin film solar cell is enhanced from 2.07% to 3.92%. The photoelectric performance enhancement mechanism is analyzed by the measurements of electrochemical impedance spectroscopy and intensity modulating photoelectrochemical spectroscopy of CZTS thin film solar cells and certificated to be formation of the bigger CZTS grains due to addition of hydroxypropyl cellulose, which reduces the boundary defects and makes the film surface be more continuous. These results suggest that addition of hydroxypropyl cellulose into the precursor solution is an effective way to obtain high performance CZTS thin film solar cells.

The effect of annealing conditions: temperature, time, ramping rate and atmosphere on nanocrystal Cu2ZnSnS4 (CZTS) thin film solar cell properties

Abstract Cu2ZnSnS4 (CZTS) nanoparticles were fabricated successfully using the hot injection method; CZTS films were deposited by spin coating of nanocrystal ink. The aim of this work is to study the effect of annealing parameters: temperature, time, ramping rate and atmosphere on CZTS thin film structure and optical properties. XRD, Raman Spectroscopy, SEM, EDX mapping are used to analyse the films and they demonstrate the increase in quality and improvement in the crystallinity of CZTS and the homogeneity of elements which is one of the important factors for CZTS thin film solar cells. The crystallinity, structure and chemical composition of CZTS thin films increased and improved under annealing in H2S+N2 atmosphere which demonstrated that annealing at 500 oC for 1 h with a ramping rate of 10 oC/min under H2S+N2 atmosphere is a suitable condition for the fabrication of CZTS thin films used in solar cell devices.

Elucidating the role of interfacial MoS2 layer in Cu2ZnSnS4 thin film solar cells by numerical analysis

In this study, the effects of transition metal dichalcogenide, MoS2 interfacial layer formation between the Cu2ZnSnS4 (CZTS) absorber layer and Mo back contact in a conventional CZTS thin film solar cell (TFSC) structure have been studied by numerical simulation using wxAMPS-1D software. The goal of this study is to elucidate the effects of both n and p-type MoS2 on the overall CZTS solar cell’s performance from the viewpoint of metal-semiconductor junction and heterojunction band alignment. Interestingly, CZTS device, regardless of p or n-type MoS2 largely outperforms device without any MoS2 due to lower back contact barrier value. Significant transition in efficiency is noticed when acceptor (increases efficiency) or donor (decreases efficiency) concentration has a transition from 1016 cm−3 to higher concentration of 1018 cm−3 or more. Also, effect of variable electron affinity and band gap of MoS2 has been discussed from band alignment perspective. Generally, MoS2 layer with lower electron affinity and band gap is preferred to induce desirable band alignment and subsequently result in higher efficiency. All-in all, the formation of p-type MoS2 in CZTS solar cells can be tuned to improve the cell performance mainly by doping with higher acceptor doping concentration and limiting layer thickness. However, the detrimental effect of n-MoS2 can be prevented by maintaining thinner layer in the vicinity of ∼30 nm with low to moderate donor doping (<1016 cm−3).