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Due to the optical properties of the electron transport layer (ETL) and hole transport layer (HTL), inverted perovskite solar cells can perform better than traditional perovskite solar cells. It is essential to compare both types to understand their efficiencies. In this article, we studied inverted perovskite solar cells with NiOx/CH3NH3Pb3/ETL (ETL = MoO3, TiO2, ZnO) structures. Our results showed that the optimal thickness of NiOx is 80 nm for all structures. The optimal perovskite thickness is 600 nm for solar cells with ZnO and MoO3, and 800 nm for those with TiO2. For the ETLs, the best thicknesses are 100 nm for ZnO, 80 nm for MoO3, and 60 nm for TiO2. We found that the efficiencies of inverted perovskite solar cells with ZnO, MoO3, and TiO2 as ETLs, and with optimal layer thicknesses, are 30.16%, 18.69%, and 35.21%, respectively. These efficiencies are 1.5%, 5.7%, and 1.5% higher than those of traditional perovskite solar cells. Our study highlights the potential of optimizing layer thicknesses in inverted perovskite solar cells to achieve higher efficiencies than traditional structures.

This paper focuses on exploring new materials and structure as a means to increase the efficiency of solar cells. Since silicon is widespread on earth, it is desirable to study heterojunction solar cells made mainly of silicon and new materials. Therefore, ZnO/Si and TiO2/Si heterojunction solar cells were studied in this paper. First, the electrical and optical properties of ZnO and TiO2 were determined using the Perdew-Burke-Ernzerhof (PBE), PBE functional revised for solids (PBESol) and Perdew-Wang (PW91) functionals of the Generalized gradient approximation (GGA) in Density Functional Theory (DFT). The obtained results in various functionals are assessed and analyzed. It was found that geometric optimized structures of TiO2 and ZnO is mechanical stable. Accordingly, in all functionals, the effective mass of the electron in ZnO and TiO2 proved to be smaller than that of the hole. The mobility of electrons and holes in ZnO was calculated to be 430.72 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ and 5.25 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ respectively. In TiO2, it was 355.27 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ and 46.38 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ . When PW91, PBESol, PBE functionals were used, the dielectric constant was determined to be 11, 11.5, 8.5 for ZnO and 9.5, 10, 9 for TiO2, respectively. According to the DFT results, it was determined that ZnO and TiO2 are transparent and mainly n-type direct semiconductors. According to device simulation, the maximum short-circuit current of ZnO/Si and TiO2/Si heterojunction solar cells is 18 mA/cm2 at a thickness of 80 nm and 15.3 mA/cm2 at a thickness of 40 nm. Finally, the average fill factor of ZnO/Si and TiO2/Si solar cells was 0.73 and 0.76 respectively. So TiO2 can be used as a transparent contact and ZnO as an emitter layer in a silicon-based solar cell.

Metal oxides are commonly used in optoelectronic devices due to their transparency and excellent electrical conductivity. Based on its physical properties, each metal oxide serves as the foundation for a unique device. In this study, we opt to determine and assess the physical properties of MoO3 metal oxide. Accordingly, the optical and electronic parameters of MoO3 are evaluated using DFT (Density Functional Theory), and PBE and HSE06 functionals were mainly used in the calculation. It was found that the band structure of MoO3 calculated using PBE and HSE06 exhibited indirect semiconductor properties with the same line quality. Its band gap was 3.027 eV in HSE06 and 2.12 eV in PBE. Electrons and holes had effective masses and mobilities of 0.06673, −0.10084, 3811.11 cm2V−1s−1 and 1630.39 cm2V−1s−1, respectively. In addition, the simulation determined the dependence of the real and imaginary components of the complex refractive index and permittivity of MoO3 on the wavelength of light, and a value of 58 corresponds to the relative permittivity. MoO3 has a refractive index of between 1.5 and 3 in the visible spectrum, which can therefore be used as an anti-reflection layer for solar cells made from silicon. In addition, based on the semiconducting properties of MoO3, it was estimated that it could serve as an emitter layer for a solar cell containing silicon. In this work, we calculated the photoelectric parameters of the MoO3/Si heterojunction solar cell using Sentaurus TCAD (Technology Computing Aided Design). According to the obtained results, the efficiency of the MoO3/Si solar cell with a MoO3 layer thickness of 100 nm and a Si layer thickness of 9 nm is 8.8%, which is 1.24% greater than the efficiency of a homojunction silicon-based solar cell of the same size. The greatest short-circuit current for a MoO3/Si heterojunction solar cell was observed at a MoO3 layer thickness of 60 nm, which was determined by studying the dependency of the heterojunction short-circuit current on the thickness of the MoO3 layer.

Perovskite solar cells (PSCs) are a promising area of research among different new generations of photovoltaic technologies. Their manufacturing costs make them appealing in the PV industry compared to their alternatives. Although PSCs offer high efficiency in thin layers, they are still in the development phase. Hence, optimizing the thickness of each of their layers is a challenging research area. In this paper, we investigate the effect of the thickness of each layer on the photoelectric parameters of n-ZnO/p-CH3NH3PbI3/p-NiOx solar cell through various simulations. Using the Sol–Gel method, PSC structure can be formed in different thicknesses. Our aim is to identify a functional connection between those thicknesses and the optimum open-circuit voltage and short-circuit current. Simulation results show that the maximum efficiency is obtained using a perovskite layer thickness of 200 nm, an electronic transport layer (ETL) thickness of 60 nm, and a hole transport layer (HTL) thickness of 20 nm. Furthermore, the output power, fill factor, open-circuit voltage, and short-circuit current of this structure are 18.9 mW/cm2, 76.94%, 1.188 V, and 20.677 mA/cm2, respectively. The maximum open-circuit voltage achieved by a solar cell with perovskite, ETL and HTL layer thicknesses of (200 nm, 60 nm, and 60 nm) is 1.2 V. On the other hand, solar cells with the following thicknesses, 800 nm, 80 nm, and 40 nm, and 600 nm, 80 nm, and 80 nm, achieved a maximum short-circuit current density of 21.46 mA/cm2 and a fill factor of 83.35%. As a result, the maximum value of each of the photoelectric parameters is found in structures of different thicknesses. These encouraging results are another step further in the design and manufacturing journey of PSCs as a promising alternative to silicon PV.