The study of inorganic absorber layers in perovskite solar cells: The influence of CdTe and CIGS incorporation

Abstract The perovskite solar cell has been the subject of intense breakdown lately because of its exceptional efficiency. Nevertheless, they confront a significant challenge due to the absorber layer's (perovskite) sensitivity to oxygen and water, which can cause rapid material degradation and adversely affect the solar cell's performance. The commonly used organic hole transport layer (HTL), Spiro-OMeTAD, tends to degrade over time, exacerbating the issue. To address this challenge, two-stage research was conducted. Initially, the CH3NH3PbI3 thin film was experimentally prepared, and XRD analysis confirmed the material's satisfactory crystalline phase (tetragonal), with a crystal size of 73.9 nm. An energy band gap of 1.55 eV was obtained experimentally, demonstrating good correspondence with the literature. Then, perovskites with different crystal structures (cubic, tetragonal, and orthorhombic) were calculated by DFT. These calculations obtained energy band gaps with values of 1.5 eV for the cubic, 1.7 eV for the tetragonal, and 3.9 eV for the orthorhombic. Subsequently, a numerical simulation study using SCAPS was carried out to validate the theoretical performance of an experimental solar cell with Spiro-OMeTAD as the HTL. Also, a simulation without HTL was performed to highlight its importance. Finally, comparative studies were conducted to evaluate the feasibility of using CdTe and CIGS as inorganic absorbing layers to replace Spiro-OMeTAD. The study found that the CIGS absorbent layer outperformed Spiro-OMeTAD and CdTe, achieving an efficiency of 15.67%. Additionally, a CIGS absorbent layer optimization study was conducted, returning various output parameter values, including an efficiency of 28.32%. This study recommends implementing a CIGS absorbent layer as HTL to replace Spiro-OMeTAD due to its superior performance and inorganic nature. This research represents a significant advancement in developing stable and efficient perovskite solar cells.