Optoelectronic modeling of all-perovskite tandem solar cells with design rules to achieve >30% efficiency

Abstract

All-perovskite tandem solar cells pave the way for increasing the efficiency of solar cells beyond the Shockley-Queisser limit imposed on single junction perovskite cells. While all-perovskite tandem solar cells with high power conversion efficiency (PCE) of 24.8% have been fabricated, the understanding of the underlying device physics during their operation still remains unclear. In this work we present an optoelectronic model for monolithic all-perovskite tandem solar cell. This coupled model incorporating transfer matrix model for optical effects, and drift diffusion model for electrical effects accurately describes the photophysical and optoelectronic processes occurring in the all-perovskite tandem cell. The results of this model have been verified with results from a recent published experimental work on all-perovskite tandem cell with 24% PCE and show good agreement. The key parameters governing the PCE of tandem solar cells, such as trap density in active layer, recombination layer resistance, carrier mobility and absorber layer thicknesses are evaluated to establish design rules to attain greater than 30% PCE for all-perovskite tandem solar cells. Even though this model has been developed for an all-perovskite tandem solar cell, the principle guiding the model is general and can be applied to any type of tandem photovoltaic technology.