Hole transport material (HTM) plays an important role in the efficiency and stability of perovskite solar cells (PSCs). Spiro-MeOTAD, the commonly used HTM, is costly and can be easily degraded by heat and moisture, thus offering hindrance to commercialize PSCs. There is dire need to find an alternate inorganic and stable HTM to exploit PSCs with their maximum capability. In this paper, a comprehensive device simulation is used to study various possible parameters that can influence the performance of perovskite solar cell with CuI as HTM. These include the effect of doping density, defect density and thickness of absorber layer, along with the influence of diffusion length of carriers as well as electron affinity of electron transport layer (ETM) and HTM on the performance of PSCs. In addition, hole mobility and doping density of HTM is also investigated. CuI is a p-type inorganic material with low cost and relatively high stability. It is found that concentration of dopant in absorber layer and HTM, the electron affinity of HTM and ETM affect the performance of solar cell minutely, while cell performance improves greatly with the reduction of defect density. Upon optimization of parameters, power conversion efficiency for this device is found to be 21.32%. The result shows that lead-based PSC with CuI as HTM is an efficient system. Enhancing the stability and reduction of defect density are critical factors for future research. These factors can be improved by better fabrication process and proper encapsulation of solar cell.

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Recently, perovskite solar cells (PSCs) have achieved remarkable power conversion efficiency (PCE) about 22.6%. While most of the hole transport materials (HTMs) used in PSCs are organic in nature with an issue of instability and high cost. In this paper, copper thiocyanate (CuSCN), a low cost inorganic HTM with excellent thermal and moisture stability, is applied as HTM for perovskite solar cells. The device modeling of PSCs is based on the device structure of FTO/TiO 2 /MAPbI 3 /CuSCN/Au. Two interface defect layers, IDL1 as electron transport material (ETM)/absorber interface and IDL2 as absorber/HTM interface, are introduced into the device model in order to study the impact of interface quality on the performance of PSCs. Among all of the parameters, defect density and conduction band offset (CBO) at ETM/ absorber interface together with the defect density of absorber influence the device performance appreciably. Upon optimization of all of the parameters, PCE of the device approaches to 25.02%, which is very encouraging. The result shows that lead-based PSC with CuSCN as HTM is an efficient system due to its enhanced hole transport, high electric conductivity, and improved chemical interaction with absorber. Further, defect density of ETM/absorber interface and absorber layer could be reduced by optimized deposition process.

Inverted perovskite solar cells (p-i-n PSCs) have been fascinated due to rapid progress of performance in recent years. PEDOT: PSS is commonly used hole transport material (HTM) in p-i-n PSCs which is hygroscopic and acidic in nature that leads towards poor performance of device thus hinders commercialization of PSCs. Therefore, it is necessary to replace PEDOT: PSS with stable HTM in p-i-n PSCs. In this paper, theoretical study is carried out to investigate various physical parameters that can affect the performance of p-i-n PSCs with copper iodide (CuI) as HTM and phenyl-C61-butyric acid methyl ester (PCBM) as ETM. These parameters include the effect of doping density of ETM, absorber, and HTM as well as defect density and thickness of absorber on the performance of p-i-n PSCs. In addition, hole mobility and thickness of HTM is also investigated. It is found that performance of p-i-n PSC is strongly dependent on defect density and thickness of absorber layer while other physical parameters have minor influence on the performance of device. Upon final optimization, device attains PCE of more than 21 % which is encouraging. These results show that CuI as HTM is a potential choice for p-i-n PSCs.

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