Enhancing the stability of perovskite solar cells through cross-linkable and hydrogen bonding multifunctional additives

Ion migration, especially I- migration, is a main issue limiting the stability of perovskite solar cells (PSCs). Here, we introduce a multifunctional additive of dipentaerythritol pentaacrylate (DPPA) into perovskite films to suppress the ion migration. The CH2CH groups in DPPA will crosslink at grain boundaries and block the channels of ion migration. Importantly, the alkoxy (-O-CH2) and hydroxyl (-OH) groups in DPPA can bond with the FA+ and I- ions in the perovskite through hydrogen interaction, chemically immobilizing these migrated ions. As a result, ion migration in the perovskite is effectively inhibited owing to the synergistic function of DPPA. PSCs with DPPA exhibit a high efficiency of over 22% with good operational stability, retaining over 90% of maximum efficiency after maximum power point (MPP) tracking for 800 hours under continuous illumination. In addition, the air and thermal stabilities are also enhanced and over 90% of initial efficiency is retained after aging in air or at 85 °C for 1000 hours.