Chemical Bath Deposition Method Research Articles

Surface Modification of TiO2 for High Performance in all Inorganic Perovskite Solar Cells

Titanium dioxide (TiO[Formula: see text] is a commonly employed electron transport layer in perovskite solar cells (PSCs) due to its exceptional attributes such as high mobility, a wide bandgap and remarkable stability against moisture and high temperatures. This holds particularly true for inorganic PSCs. Nevertheless, the substantial hysteresis and elevated trap defect levels following annealing present challenges to enhance the efficiency of the PSCs. Herein, we proposed a chemical bath deposition (CBD) method to fabricate the TiO2 layer, serving as the electron transport layer in CsPbBr3 solar cells. This method is coupled with KCl, which supplies an ample quantity of [Formula: see text] ions capable of diffusing into the CsPbBr3 perovskite film during the annealing process. The inclusion of [Formula: see text] ions significantly diminishes the solar cell hysteresis and enhances the crystalline quality of the perovskite material, thereby enhancing the performance of CsPbBr3 solar cells. By implementing the TiO2 and KCl treatments, we achieved an impressive efficiency of 9.49%. Furthermore, the device also exhibited excellent stability in air for 30 days.

Chemical Bath Deposition of Planar Nickel Oxide Films for Inverted Perovskite Solar Cells and Mini‐Modules

Chemical bath deposition (CBD) is an economical method for the large‐scale preparation of high‐quality inorganic transport layers. In the field of the n–i–p perovskite solar cells (PSCs), the devices based on n‐type CBD–SnO2/CBD–TiO2 structures demonstrate significant advantages in efficiency and stability. However, using CBD method to deposit high‐quality planar p‐type NiOx is challenging due to the anisotropic growth of nickel‐based intermediate phase. Herein, NH4Cl additive is introduced to modulate the intermediate phase by adjusting the concentration of [Ni(H2O)x(NH3)6−x]2+ cations. As a result, dense and uniform NiOx films are finally obtained after thermal annealing. Simultaneously, the energy level and hole conductivity of NiOx materials are carefully controlled by adjusting the annealing temperature. Benefited from the excellent electronic properties of CBD–NiOx hole‐transport layer, the inverted PSCs based on MAPbI3, (FA0.98MA0.02)0.95Cs0.05Pb(I0.95Br0.05)3 achieve the power conversion efficiency of 19.75% and 23.30%, respectively. Furthermore, the unencapsulated devices maintain over 90% of their initial efficiency after continuous operation for 700 h. Scaling up this novel intermediate phase regulation CBD method yields a mini‐module with an active area of 14 cm2, achieving an efficiency of 19.36%.

Binderless synthesis of hierarchical, marigold flower-like NiCo2O4 films for high-performance symmetric supercapacitor

The facile and cost-effective chemical bath deposition method is employed for the binder-free synthesis of NiCo2O4 marigold flower-like nanostructures on a flexible stainless-steel substrate. Binderless and surfactant-free synthesis of NiCo2O4 films for supercapacitor application is a crucial part of this synthesis process. The effect of reaction times on the deposition of NiCo2O4 nanostructured films has been discussed briefly based on the electrochemical performance and surface morphology of films. The reaction time is varied as 2, 4, 6, and 8 h. The prepared films were analyzed by structural and morphological characterizations. The time-dependent significant change in morphology of NiCo2O4 films is discussed in detail. The development of the Marigold-like flowers from wheat grain-like nanostructures has been observed for increasing reaction time. The film deposited at 6 h reaction time (NCO-6 electrode) showed better specific capacitance of 1277 F/g at 5 mA/cm2, which retained about 95 % after 10,000 cycles. The NiCo2O4 film exhibited a 0.7 V potential window with the maximum energy and power density of 86 Wh/kg and 2333 W/kg, respectively. The fabricated aqueous symmetric device i.e., NCO//NCO showed energy density and power density of 16.4 Wh/kg and 275.5 W/kg, respectively. The fabricated device shows 90.5 % retention in performance after 5000 cycles. These results revealed that NiCo2O4 can be a better electrode material for energy storage devices.

Enhancement of Photo-Electrical Properties of CdS Thin Films: Effect of N2 Purging and N2 Annealing

The impact of N2 purging in the CdS deposition bath and subsequent N2 annealing is examined and contrasted with conventional CdS films, which were deposited without purging and annealed in ambient air. All films were fabricated using the chemical bath deposition method at a temperature of 80 °C on fluorine-doped tin oxide glass slides (FTO). N2 purged films were deposited by introducing nitrogen gas into the deposition bath throughout the CdS deposition process. Subsequently, both N2 purged and un-purged films underwent annealing at temperatures ranging from 100 to 500 °C for one hour, either in a nitrogen or ambient air environment. Photoelectrochemical (PEC) cell studies reveal that films subjected to both N2 purging and N2 annealing exhibit a notable enhancement of 37.5% and 27% in ISC (short-circuit current) and VOC (open-circuit voltage) values, accompanied by a 5% improvement in optical transmittance compared to conventional CdS thin films. The films annealed at 300 °C demonstrate the highest ISC, VOC, and VFB values, 55 μA, 0.475 V, and −675 mV, respectively. The improved optoelectrical properties in both N2-purged and N2-annealed films are attributed to their well-packed structure, enhanced interconnectivity, and a higher sulfur to cadmium ratio of 0.76 in the films.

Emerging pathways in thermoelectric: Chemical bath deposition of magnesium selenide thin films for sustainable energy harvesting

In this study, magnesium Selenide (MgSe) thin films were synthesized on glass substrate using the chemical bath deposition (CBD) method for thermoelectric power generation. After cleaning of glass substrate, selenium powder was dissolved in nitric acid to produce SeO2 and magnesium chloride was then introduced as the source of magnesium. Both SeO2 and MgCl2 were dissolved in 100 ml of dI water and later, these solutions were unified gradually. After that, the cleaned glass substrates were placed in the solution, while keeping the reaction temperature constant at 50o C for the deposition durations of 24, 48, 72, and 96 h. A number of characterization techniques, namely X-ray Diffraction (XRD), Raman spectroscopy and Scanning Electron Microscopy (SEM) were performed for structural and surface analysis of grown thin films. The effect of deposition time duration on the thermoelectric properties was investigated in depth using the Seebeck and Hall systems. It was found that the values of the Seebeck coefficient and power factor obey the increasing trend with maximum values 196.93 μV/K and 21.5 × 10−8 W/mK2 respectively. These observed values are seems to be the highest values for magnesium selenide thin film ever reported in the literature according to the best of our knowledge. Therefore, we have concluded that MgSe thin films supposed to be emerging material for thermoelectric power generation applications.

Improvement of the photoelectrical properties of chemical bath-deposited Sb2S3 thin films with low copper doping

The chemical bath deposition method was used to prepare Cu-doped Sb2S3 thin films from complexes of Cu and Sb with triethanolamine. The as-deposited films with orange coloration had good adherence to the substrate. After an annealing treatment at 300 °C for 30 min in an Ar atmosphere, the resulting films acquired a brown color and exhibited the orthorhombic phase of Sb2S3 with the preferential growth of [hk0] grains. The Sb2S3 films were formed by rod-shaped nanoparticles, while the insertion of Cu ions in Sb2S3 promoted the formation of ribbon-like structures. The analysis of optical properties indicated the narrowing of bandgap energy from 1.9 to 1.8 eV due to the presence of Cu ions. In addition, the photoconductivity of the films increased from 8.3 × 10–6 to 30.5 × 10–6 Ω−1cm−1, while the photosensitivity factor was enhanced by more than 3 times. The performance of photovoltaic devices based on CdS/Sb2S3 and CdS/Cu:Sb2S3 heterojunctions were investigated. Compared with the device using a Sb2S3 layer, the one using a Cu-doped Sb2S3 layer exhibited an increase in open circuit voltage from 118.2 to 205 mV, short circuit current density from 0.14 to 0.34 mA/cm2 and conversion efficiency from 0.02 to 0.12%. The best performance was obtained by a photovoltaic device with a 500 nm Cu-doped Sb2S3 layer reaching an open circuit voltage of 226 mV, a short circuit current density of 0.94 mA/cm2 and conversion efficiency of 0.32%.

Effect of Deposition Time on Material Properties of ZnO Nanorods Grown on GZO Seed Layer by CBD

ZnO nanorods (ZNRs) were grown on Ga-doped ZnO (GZO) through a two-step procedure, involving pre-treatment to form the seed layer followed by growth of the nanorods through chemical bath deposition (CBD) method

Optical Characterization of Ferric-Doped ZnO Thin Film Deposited By Chemical Bath Deposition Method

Fe-doped ZnO holds numerous potential uses in devices such as UV light emitters, piezoelectric transducers, transparent electronics in solar cells, and bright windows as an II-VI semiconductor material. This study looked into the band gap, surface characteristics, optical transmittance, and absorbance of ZnO thin films with Fe doping in different pH conditions such as 8, 9, and 10. The films were prepared using the chemical bath deposition (CBD) method at 350 °C on a glass substrate. The samples were characterized using UV-visible spectroscopy and scanning electron microscopy (SEM). The SEM images of the undoped samples exhibited a lack of cracks, but the doped samples displayed visible cracks due to the presence of Fe in the films. ZnO thin-film surface shape is altered by pH and Fe doping variations. There is a tendency for the films' visual transmission to decrease when the pH rises. The absorbance for all samples increases in the UV and declines in the visible. Fe doping causes the optical band gap Eg to drop. The band gap of both doped and undoped samples reduces when pH rises.

Green and Facile Synthesis of Zn3V2O8−Ag@C Composite as an Efficient Electrode for Supercapacitor Application

AbstractThe present study demonstrates the synthesis of ternary composites of zinc vanadate (Zn3V2O8) with silver (Ag) and carbon matrix originated from the Bengal gram bean extract (BGBE) using a facile, economic, and environmentally sustainable rotational chemical bath deposition (R−CBD) method. From the electrochemical studies, it is found that the Zn3V2O8−Ag@C demonstrated improved electrochemical performance with the specific capacitance (Csp) of 380.1 F g−1, energy density (ED) of 52.7 Wh kg−1, with power density (PD) of 882.3 W kg−1 at 3 mA cm−2 current density and good capacitive retention of 89.8 % over 3000 charge–discharge (GCD) cycles, which is remarkably higher than the other electrode materials (Zn3V2O8, Zn3V2O8−Ag, Zn3V2O8@C). The combined merits of conductive silver (Ag) nanoparticle and carbonaceous material from BGBE assist in enhancing the overall electrochemical performance of Zn3V2O8−Ag@C. The Zn3V2O8−Ag@C nanocomposite was used as electrode material for the fabrication of a flexible symmetric solid–state supercapacitor device (SSC). The SSC device delivered a Csp of 69.17 F g−1 with an energy density (ED) of 13.8 Wh kg−1 at a 2 mA cm−2 current density. Moreover, the SSC shows a 90 % capacitive retention over the continuous GCD cycles.

Deep-Level Transient Spectroscopy Studies on Four Different Zinc Oxide Morphologies

In this work, we described the variations in the defect energy levels of four different ZnO morphologies, namely nanoribbons, nanorods, nanoparticles, and nanoshuttles. All the ZnO morphologies were grown on a seeded 4% Boron-doped p-type silicon (p-Si) wafer by using two different synthesis techniques, which are chemical bath deposition and microwave-assisted methods. The defect energy levels were analyzed by using the Deep-Level Transient Spectroscopy (DLTS) characterization method. The DLTS measurements were performed in the 123 K to 423 K temperature range. From the DLTS spectra, we found the presence of different trap-related defects in the synthesized ZnO nanostructures. We labeled all the traps related to the four different ZnO nanostructures as P1, P2, P3, P4, and P5. We discussed the presence of defects by measuring the activation energy (Ea) and capture cross-section (α). The lowest number of defect energy levels was exhibited by the ZnO nanorods at 0.27 eV, 0.18 eV, and 0.75 eV. Both the ZnO nanoribbons and nanoparticles show four traps, which have energies of 0.31 eV, 0.23 eV, 0.87 eV, and 0.44 eV and 0.27 eV, 0.22 eV, 0.88 eV, and 0.51 eV, respectively. From the DLTS spectrum of the nanoshuttles, we observe five traps with different activation energies of 0.13 eV, 0.28 eV, 0.25 eV, 0.94 eV, and 0.50 eV. The DLTS analysis revealed that the origin of the nanostructure defect energy levels can be attributed to Zinc vacancies (Vzn), Oxygen vacancies (Vo), Zinc interstitials (Zni), Oxygen interstitials (Oi), and Zinc antisites (Zno). Based on our analysis, the ZnO nanorods showed the lowest number of defect energy levels compared to the other ZnO morphologies.

Synthesis and Characterization of Hierarchical Structure Au/ZnO Nanocomposites for Possible Photocatalytic Applications

Semiconductor-metal nanocomposites are actively investigated for their diverse applications in emerging fields such as photocatalysis, photovoltaics, and chemical sensing. In this study, we synthesized ZnO semiconductor nanoparticles using a chemical bath deposition method with ZnSO4·7H2O and controlled NH4OH concentrations, facilitated by an anionic surfactant to enable the attachment of Au metal nanoparticles. Au nanoparticles were prepared from HAuCl4 using citrate as a reducing agent, and metal oxide was rapidly introduced to ensure a well-defined nanocomposite with a fixed 75 w/v% composition. Fast Fourier transform spectroscopy (FTIR) and Ultra-visible (UV-Vis) spectroscopy were used to provide clear evidence of Au/ZnO nanocomposite formation through the presence of distinctive peaks around 359nm and 518nm, with Dynamic Light Scattering (DLS) revealing contrasting average sizes for ZnO and Au, highlighting the significant size difference in the Au/ZnO nanocomposites. Additionally, the scanning electron microscopy – energy dispersive x-ray (SEM-EDS) analysis confirmed the successful presence of ZnO nanoparticles. These findings offer insights into the potential applications and unique properties of Au/ZnO nanocomposites for possible photocatalytic applications.

Area-Selective Growth of Zinc Oxide Nanowire Arrays for Piezoelectric Energy Harvesting.

In this work, we present the area-selective growth of zinc oxide nanowire (NW) arrays on patterned surfaces of a silicon (Si) substrate for a piezoelectric nanogenerator (PENG). ZnO NW arrays were selectively grown on patterned surfaces of a Si substrate using a devised microelectromechanical system (MEMS)-compatible chemical bath deposition (CBD) method. The fabricated devices measured a maximum peak output voltage of ~7.9 mV when a mass of 91.5 g was repeatedly manually placed on them. Finite element modeling (FEM) of a single NW using COMSOL Multiphysics at an applied axial force of 0.9 nN, which corresponded to the experimental condition, resulted in a voltage potential of -6.5 mV. The process repeated with the same pattern design using a layer of SU-8 polymer on the NWs yielded a much higher maximum peak output voltage of ~21.6 mV and a corresponding peak power density of 0.22 µW/cm3, independent of the size of the NW array. The mean values of the measured output voltage and FEM showed good agreement and a nearly linear dependence on the applied force on a 3 × 3 µm2 NW array area in the range of 20 to 90 nN.

Photoelectrochemical Properties and Characterization of CdS/CdSe Heterojunctions Obtained by CBD on ITO and p–Si Substrates

AbstractThis research investigates the optical, structural, electrical, and photoelectrochemical characteristics of CdS/CdSe heterojunctions formed on both ITO and p–Si substrates. The deposition of CdS and CdSe films was carried out using the chemical bath deposition method, which is economical and simple method. The optical, structural, and electrical properties of CdS/CdSe heterojunctions were analyzed through UV–Vis spectrometry, photoluminescence (PL) spectroscopy, field emission–scanning electron microscopy (FE‐SEM), X‐ray diffraction (XRD), Raman spectroscopy, and Hall‐effect measurements. Furthermore, Mott–Schottky analysis was employed to investigate the electrochemical properties of the semiconductor CdS/CdSe heterojunctions on both ITO and p–Si substrates. Additionally, the photoelectrochemical investigations of CdS/CdSe heterojunctions on ITO and p–Si substrates were conducted by electrochemical analyses using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and photocurrent – time plots under both dark and illuminated conditions.

Function‐Oriented Design of Amorphous MoS2 with Abundant Active Sites for High‐Efficiency Hydrogen Evolution Reaction

AbstractMolybdenum disulfide (MoS2) has received great interest as a highly active and cost‐effective electrocatalyst for hydrogen evolution reaction (HER). However, a main challenge for developing high‐efficiency electrocatalysts is to tailor the factors affecting the HER performance, such as composition, structure, and morphology. Herein, amorphous MoS2 electrodes with different Mo and S contents are successfully synthesized by the chemical bath deposition method using different molar ratios of Mo/S precursors (Mo/S: 4 : 1, 1 : 1 and 1 : 4) at various growth times. Experimental results indicate that the composition and the surface morphology of MoS2 are strongly sensitive to the Mo and S contents, which can create different surface roughness at the interface induced by growth times. The as‐prepared MoS2 electrode with a molar ratio of 1 : 4 exhibits superior HER activity in 1 M KOH, only requiring low overpotentials of 220 mV at 20 mA cm−2, which is much lower than those of MoS2 with a molar ratio of 1 : 1 (253 mV), and 4 : 1 (290 mV), respectively. This outstanding electrochemical performance of MoS2 (Mo/S, 1 : 4) with excellent long‐term stability can be attributed to its unique sulfur‐rich MoS2 nanosheet array structure with exposed abundant active sites, a high electrochemical active surface area (ECSA: 955.50 cm2) and superior roughness factor (RF: 3822).

Optical and electrical properties of Ni+2 doped nanocrystalline Bi2S3 thin films prepared by chemical bath deposition method

Nickel (Ni+2) doped nanocrystalline Bi2S3 thin films are deposited on the glass substrate from the solutions containing Bismuth Nitrate, Ethylenediamine Tetraacetic acid (EDTA) and Thioacetamide at a bath deposition temperature of 318K. The optical, surface morphological and electrical properties of Ni-doped Bi2S3 thin films prepared at three different doping concentration are investigate by using ultraviolet–visible transmission spectra (UV–Vis), Scanning electron microscopy (SEM), Energy Dispersive X-ray (EDAX) and thermo-e.m.f. techniques. The optical band gap energies are found in between 2.32-2.43 eV. The SEM images show that the prepared films are continuous, dense and distributed over the entire area with good uniformity. The electrical conductivity of the films are in the order of 10-2 Ω-1 m-1 . The films are n-type as determined from the Hot Probe method. Photoconductivity studies reveal that photocurrent increases with the increase in Ni doping concentrations. Due to the absorption of photons, free electron-hole pairs (EHP) are produce.

Synthesis of Template-free Flower-like ZnO Nanorods using a Simple Chemical Bath Technique

Flower-like ZnO nanorods were successfully synthesised using a template-free, low-temperature chemical bath deposition method. The effects of growth time on the structural, morphological, and vibrational properties of flower-like zinc oxide were investigated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that the crystallite size and density of flower-like ZnO nanorods increased with increasing growth time. Raman spectroscopy confirmed the existence of specific Raman modes that correspond to the wurtzite structure of ZnO. In addition, Raman measurements revealed that increased growth time increases the Raman modes intensity of the flower-like ZnO nanorods. Moreover, the measurements of the Au/ZnO nanorods/FTO Schottky diode showed that all devices functioned as Schottky diodes and rectifying; however, their ideality factor was greater than 1. In addition to the ideality factor, the Schottky barrier height was calculated and slightly increased with growth time. The values of Schottky barrier height obtained were 0.502 eV, 0.523 eV, 0.516 eV and 0.529 eV for samples grown at 1, 2, 3 and 4 h, respectively.

Synthesis and characterization of Mo-doped PbS thin films for enhancing the photocatalytic hydrogen production

Photocatalytic hydrogen production has gained considerable attention as a sustainable method for renewable energy production. Lead sulfide (PbS) compound has significant reserves and a suitable bandgap for the production of hydrogen gas via the water photo-splitting process. However, the charge recombination effect of the charge carriers severely limits their potential use in solar water splitting. Herein, the photoelectrodes of PbS were fabricated through the chemical bath deposition method and then doped with different Mo concentrations to optimize the hydrogen photo-production activity. Both structural and performance characterizations of the photoelectrodes have been carried out using various characterization techniques. The photoelectrochemical (PEC) performance of molybdenum (Mo)-doped PbS photoelectrodes exhibits a significant increase in the photocurrent density with the optimum photocurrent density of 1.2 mA/cm2 obtained at 0.8 % Mo doping atomic ratio which was twelve times higher than that of a pure PbS photoelectrode. The doping of Mo induces the electron-hole separation yield which results in improved electron transport characteristics. The Mo doping was as act as a donor site that increased the PbS film conductivity. The newly optimized Mo–PbS was used as a promising photoelectrode supported on commercial glass using the optimum Mo-doped PbS photoelectrode, the photoelectrochemical (PEC) hydrogen production rate was reached 122 μmol/h cm2 during the solar water splitting process and the conversion efficiency of the incident photon-to-current (IPCE) value was 7.0 % at 390 nm monochromatic exposure. Moreover, the stability of the optimum electrode was evaluated as a function of the number of runs and exposure time in addition to the electrochemical impedance study.

Optical transmission and photoconductivity of chemical bath-deposited CdS thin films for optoelectronic applications

This paper presents a comprehensive study of the optical transmission, photoconductivity, and morphology of CdS thin films deposited via the chemical bath deposition (CBD) method. The films deposited for 60 min exhibit an optical energy band gap value of 2.42 eV and the highest optical transmission of 75 % in the wavelength range of 500–900 nm. For these films, the transmission electron microscopy imaging shows a distribution of particle sizes around 10 nm. The wavelength dependence of the photoconductivity, extracted from photo resistivity data, shows that the maximum photoconductivity occurs at 492 nm wavelength. This corresponds to an electrical energy band gap of 2.52 eV, which is greater than the optically measured energy gap of 2.42 eV. Based on these results, the electron-hole pair binding energy for CdS films is estimated as 100 meV. According to the electrical resistivity vs. temperature measurements, the activation energy is 1.26 eV which agrees with the electrical energy band gap of 2.52 eV. CdS films annealed under nitrogen gas at 200 °C for one hour exhibited an energy gap of 2.32 eV. These films displayed a conductivity of 60 × 10−4 Scm−1, a carrier concentration of 6.38 × 1014 cm−3, and a mobility of 7.46 cm2 V−1 s−1. These impressive characteristics suggest the suitability of CBD-grown CdS films annealed at 200 °C in nitrogen gas, to be used as the window material in CdS/CdTe thin film solar cells and other optoelectronic applications.

Solution‐based fabrication of copper oxide thin film influence of cobalt doping on structural, morphological, electrical, and optical properties

In this study, Cobalt (Co) doped Copper Oxide (CuO) films at different concentrations were deposited on glass substrates, using the Chemical Bath Deposition (CBD) method. The films were characterized by Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), Ultra Violet-Visible Spectroscopy (UV-Vis.) and two-point contact method. The FESEM images showed that nanoplates formed increased in size and voids on the films surface decreased with increasing Co concentration. The XRD patterns revealed an increase in crystallite size with increasing (from 14.40 to 18.60 nm) Co concentration and no secondary phase was formed. The Energy-dispersive X-ray spectroscopy (EDS) spectra showed the presence of Co in the film composition with increasing concentration. The results of UV-Vis. spectroscopy showed that band gap values could be changed with Co doping and thus the CuO band gap could be adjusted with the Co doping. The temperature-dependent current-voltage measurement results obtained with the two-point contact method showed that activation energy levels increased (from 0.134 to 0.232 eV) with increasing Co concentration. It was also observed that the conductivity increased with increasing temperature.

Effect of bath temperature on the efficiency and properties of Cu2O/ZnS/ZnO heterojunctions thin film prepared by electrodeposition and chemical bath deposition methods

A novel p-n type Cu2O/ZnS/ZnO heterojunction thin film was successfully fabricated by a combination of electrodeposition and chemical bath deposition techniques. The effect of bath temperature (T = 75, 80, 85, 90 °C) on the growth of ZnS layers was investigated. The influence of ZnS buffer layers on the properties and efficiency of the prepared heterojunction thin films were examined using XRD, FE-SEM, AFM, EDS, UV–Vis, and electrochemical measurements. The analysis of prepared films revealed that the Cu2O/ZnS/ZnO heterojunction exhibits a unique combination of hexagonal structure of ZnO and the cubic structure of Cu2O. It was found that all the heterojunction films exhibit the growth of composed pyramids and corner grains with a homogenous distribution. The optical band-gap of the deposited ZnS buffer layers decreased from 3.46 eV to 3.35 eV with an increase of bath temperature from 75 °C to 90 °C. Moreover, the obtained results revealed that the thicknesses and the surface roughness of ZnS buffer layers increased when bath temperature increased. Mott-Schottky results of the heterojunctions indicate a p-type semiconductor behavior for the Cu2O, while it was observed an n-type semiconductor behavior for the ZnO and ZnS layers. As a result, the photocurrent response of Cu2O/ZnO heterojunctions with ZnS layer insertion was enhanced from 0.175 to 0.730 mA, which can be attributed to the reduced electron transfer resistance, enlarged photo-generated (e−/h+) carrier separation efficiency, and enhanced light absorption due to the presence of ZnS buffer layers. These results highlight the advantages of the bath temperature on the deposition of ZnS for photoelectrochemical and solar cells applications.