An onium salt additive enhance the performance of perovskite solar cells

Abstract

Non-radiative recombination caused by defects at grain boundaries hinders the improvement of the performance of perovskite solar cells (PSCs). In this study, a bifunctional onium salt namely Pyridinium p-toluene sulfonate was added to the perovskite precursor solution. The defects of perovskite are passivated and the non-radiative recombination losses are reduced due to the sulfonic acid groups in PPTS molecules interact with Pb²⁺ and pyridine interact with I^-. It also regulates the crystallization of perovskite films, which increases the grain size and improves the crystallinity. The open circuit voltage (V_OC) of the PPTS-modified PSCs is increased from 1.03V to 1.07V, and the fill factor (FF) is increased from 75% to 78%. The resulting power conversion efficiency (PCE) of the solar cell is increased from 19.41% to 21.5%.

Keywords

perovskite / defect passivation / non-radiative recombination / onium salt / crystallization modulation