Performance optimization of homojunction perovskite solar cells by numerical simulation

Perovskite materials possess n-type and p-type electrical conductivity through a control over perovskite precursor composition and stoichiometry during the film formation. A p-n homojunction can be constituted between the p-type perovskite and the n-type perovskite and a built-in electric field is formed, which can promote the oriented transportation of the photon-generated carriers and reduce the carrier recombination losses. In this paper, the numerical simulation of p-n homojunction methylammonium lead iodide (MAPbI 3 ) solar cells has been performed and the effects of different electron transport layer (ETL) materials and hole transport layer (HTL) materials, defect density and thickness of the absorber layer and interface defect density on the device photovoltaic performance have been studied. Simulation results show that TiO 2 and Spiro-OMeTAD are the most promising ETL material and HTL material, respectively. To improve device performance, the defect density of the p-type MAPbI 3 absorber layer needs to be as low as 10 15 cm −3 and an optimal absorber thickness of 0.4 μm needs to be guaranteed. Moreover, the device performance is further improved by maintaining the interface defect density less than or equal to 10 9 cm −2 . With these optimizations, a conversion efficiency of 27.10% is achieved for the homojunction perovskite solar cells with a structure consisting of FTO/TiO 2 /n-type MAPbI 3 /p-type MAPbI 3 /Spiro-OMeTAD/Au. Hence, the device structure with perovskite homojunction provide an effective approach towards development of highly efficient solar cells. • Homojunction MAPbI 3 solar cells have been simulated with efficiency of 27.10%. • The effect of different electron transport layer and hole transport layer materials has been investigated. • The impact of bulk defect density and interface defect density has also been studied.