Tailoring lattice chlorine in perovskite through dual-additive engineering for enhanced photovoltaic performance

Abstract

The exploration of chloride residuals, originating from methylammonium chloride (MACl) – a common additive in perovskite solar cells, represents a largely unexplored frontier in the field of perovskite photovoltaics. Unveiling direct evidence and understanding the nuanced influences of these residuals on photovoltaic properties poses substantial challenges. This study, centered on printable mesoscopic perovskite solar cells (p-MPSCs), pioneers the reduction of chloride residuals infiltrating the perovskite lattice through the simultaneous incorporation of MACl and dimethylammonium chloride (DMACl) – a strategy termed as dual-additive engineering. It also delves into their effects on bandgap, energy level distribution, suppression of non-radiative recombination, Urbach energy, and shallow energy level defect distribution within the perovskite, ultimately illuminating their positive impacts on photovoltaic conversion efficiency. Density functional theory calculations suggest that the diminished chloride residuals with the introduction of DMACl alongside MACl stem from weakened ionic bonds due to alterations in molecular surface electrostatic potential, thereby curtailing the likelihood for chloride escape. This research paves the way for fresh perspectives and insights for probing chloride residual induction and executing both quantitative and qualitative analyses of trace chloride residuals in perovskite solar cells.