Contrasting Effects of Organic Chloride Additives on Performance of Direct and Inverted Perovskite Solar Cells

Perovskite solar cells (PSCs) have demonstrated encouraging progress in recent years. Additive engineering, where diverse additives are incorporated into the perovskite layer, has been widely adopted to tune the perovskite grains, reduce defect density and charge recombination. Here, we observe a universal phenomenon that organic chloride additives enhance the open circuit voltage (VOC) and power conversion efficiencies (PCEs) of direct PSCs but decrease the VOC, short-circuit current (JSC), and PCE of inverted PSCs, regardless of the choice of charge transport materials. The polyTPD-based direct device incorporating trimethylammonium chloride (TACl) additive delivery improved PCE from 17.8 to 20.0%, arising from the enhanced VOC from 1.03 to 1.12 V. With the same content of TACl, the best PCE of the polyTPD-based inverted device decreased from 20.2 to 18.5% because of the reduced VOC (1.05–1.01 V) and JSC (23.2–22.5 mA/cm2). Our investigation confirms that organic chloride will p-dope perovskites and ele...