Defect passivation using ultrathin PTAA layers for efficient and stable perovskite solar cells with a high fill factor and eliminated hysteresis

Abstract

One-step anti-solvent deposition methods are widely applied in inverted perovskite solar cells (PSCs). However, anti-solvent processed films typically exhibit a small grain size and abundant defects. Herein, we propose a facile passivation approach using an ultrathin poly(triarylamine) (PTAA) layer to passivate the interfacial and grain boundary defects. An energy band alignment is realized by introducing an ultrathin PTAA layer sandwiched between the perovskite layer and the poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) layer to suppress interfacial recombination and accelerate hole transfer. By optimum design of the PTAA layer, we fabricate PSCs with a power conversion efficiency (PCE) of 19.04%, a fill factor (FF) of 82.59% and a short-circuit current density (J_sc) of 21.38 mA cm⁻². To the best of our knowledge, the obtained FF value is the maximum among those reported for inverted chlorine-doped methyl perovskite solar cells (PSCs). After storage under ambient conditions for 10 days, the PCE of the PSCs with PTAA modification is still maintained at the 80% level, indicating substantially improved stability. Our work provides an effective method to boost PSCs with enhanced efficiency and stability.