Optoelectronic modelling of perovskite solar cells under humid conditions and their correlation with power losses to quantify material degradation

This work describes the role of relative humidity (R.H.) on the performance degradation of methyl-ammonium lead-iodide (CH3NH3PbI3) based hole transport material (HTM) free hetero-junction perovskite solar cell. It has been observed that the power conversion efficiency (η) of perovskite solar cells decreases from 4.52% to 1.28% with increases in R.H. from <40% to 75%. A semi-analytical optoelectronic model is further developed to explore the effect of humidity on performance limiting parameters, i.e. absorption coefficient, diffusion length. The shunt resistance decreases whereas space charge region width and series resistance increases with respect to the increase in R.H. from <40% to 75%. The charge carrier losses through recombination, spatial relaxation and thermalization are also analysed and found to increase from 76% at <40%R.H to 84% at 75%R.H.