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 TiO ₂ /Si heterojunction solar cells were studied in this paper. First, the electrical and optical properties of ZnO and TiO ₂ 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 TiO ₂ and ZnO is mechanical stable. Accordingly, in all functionals, the effective mass of the electron in ZnO and TiO ₂ 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 V ^-1 s ^-1 and 5.25 cm ² V ^-1 s ^-1 respectively. In TiO ₂ , it was 355.27 cm ² V ^-1 s ^-1 and 46.38 cm ² V ^-1 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 TiO ₂ , respectively. According to the DFT results, it was determined that ZnO and TiO ₂ are transparent and mainly n-type direct semiconductors. According to device simulation, the maximum short-circuit current of ZnO/Si and TiO ₂ /Si heterojunction solar cells is 18 mA/cm ² at a thickness of 80 nm and 15.3 mA/cm ² at a thickness of 40 nm. Finally, the average fill factor of ZnO/Si and TiO ₂ /Si solar cells was 0.73 and 0.76 respectively. So TiO ₂ can be used as a transparent contact and ZnO as an emitter layer in a silicon-based solar cell.

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-NiO_x 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.

It is crucial to examine the dependence of photoelectric parameters of solar cells on the light incidence angle. In the present study, two solar cell models have been developed using the Sentaurus Technology Computer-Aided Design software package. The light spectrum AM1.5 has been directed on the frontal surface of solar cells at different angles. It has been found that the angular coefficient of the photoelectric parameters of a solar cell with nanoparticles included, is two times more than that of a simple solar cell. Besides, it has been found that the efficiency of platinum nanoparticles induced solar cells is 2.15 times greater than simple solar cell efficiency. When the light incidence angle has been varied from 0 to 60 degrees, the short-circuit current has changed by 11% for simple solar cells and by 10% for solar cells with nanoparticles. Further, it has been observed that the variation of power for simple solar cells is 12.5%, while it is 10.5% for solar cells with nanoparticles. In addition, the short-circuit current of solar cells with nanoparticles has been found to be linear within a light incidence angle ranging from 0 to 60 degrees.

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.

Renewable energy sources like photovoltaics have the potential to mitigate the negative consequences of pollution and global warming. The solar sector has shown exponential growth and is quickly becoming a viable alternative to fossil fuels. Currently, the great majority of solar modules are composed of crystalline silicon. To make photovoltaics more competitive, affordability and efficiency are two of the most important elements. Metal nanoparticles can be introduced or a heterojunction can be made using appropriate materials to increase the absorption coefficient of a silicon-based solar cell, which boost the total efficiency of the solar module. Therefore, in this study, we used Sentaurus TCAD simulation to examine the effects of gold nanoparticles introduced with various sizes and periodicities on the photoelectric characteristics of ZnO/Si and Perovskite/Si solar cells. Accordingly, all of the photoelectric characteristics of the perovskite/Si solar cell have shown a clear sinusoidal connection with the nanoparticle periodicity. When the gold nanoparticle size changed from 6 nm to 9 nm, the period of the sinusoidal function changed to π. The photoelectric parameters of ZnO/Si solar cells changed in a sinusoidal pattern based on the nanoparticle’s periodicity, but this was true only when the nanoparticles size was between 9 nm and 21 nm. According to the obtained results, the maximum values of short-circuit current, open circuit voltage and fill factor are 10.47 mA/cm ² , 0.384 V, 71.06% for perovskite/Si and 10.52 mA/cm ² , 0.306 V, 71.12% for ZnO/Si. The minimum current density of the perovskite/Si solar cell was identical when compared to the solar cell without nanoparticles. When a gold nanoparticle with a size of 6 nm was introduced into the ZnO/Si solar cell with a periodicity of 120 nm, the short circuit current decreased by a factor of 3.81 compared to the solar cell without the nanoparticle. It has been scientifically proven that Fano interference is responsible for the sinusoidal relationship between the short-circuit current of the solar cells and the periodicity of the nanoparticle.

Today, it has become an important task to modify existing traditional silicon-based solar cell factory to produce high-efficiency silicon-based heterojunction solar cells, at a lower cost. Therefore, the aim of this paper is to analyze CH3NH3PbI3 and ZnO materials as an emitter layer for p-type silicon wafer-based heterojunction solar cells. CH3NH3PbI3 and ZnO can be synthesized using the cheap Sol-Gel method and can form n-type semiconductor. We propose to combine these two materials since CH3NH3PbI3 is a great light absorber and ZnO has an optimal complex refractive index which can be used as antireflection material. The photoelectric parameters of n-CH3NH3PbI3/p-Si, n-ZnO/p-Si, and n-Si/p-Si solar cells have been studied in the range of 20–200 nm of emitter layer thickness. It has been found that the short circuit current for CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells is almost the same when the emitter layer thickness is in the range of 20–100 nm. Additionally, when the emitter layer thickness is greater than 100 nm, the short circuit current of CH3NH3PbI3/p-Si exceeds that of n-ZnO/p-Si. The optimal emitter layer thickness for n-CH3NH3PbI3/p-Si and n-ZnO/p-Si was found equal to 80 nm. Using this value, the short-circuit current and the fill factor were estimated around 18.27 mA/cm2 and 0.77 for n-CH3NH3PbI3/p-Si and 18.06 mA/cm2 and 0.73 for n-ZnO/p-Si. Results show that the efficiency of n-CH3NH3PbI3/p-Si and n-ZnO/p-Si solar cells with an emitter layer thickness of 80 nm are 1.314 and 1.298 times greater than efficiency of traditional n-Si/p-Si for the same sizes. These findings will help perovskites materials to be more appealing in the PV industry and accelerate their development to become a viable alternative in the renewable energy sector.