A-site assisted perovskite crystallization via ion-exchange MOFs for high efficient and stable perovskite solar cells

Here, a novel strategy is proposed targeting the volatility of A-site cations and the disordered arrangement of perovskite grains through employing Cs+ contained metal-organic frameworks In-aip (Cs) obtained by ion-exchange and crystalline transform. Interatomic forces between Cs-O atoms split the pore channels of the pristine In-aip, endowing In-aip (Cs) with multidimensional charge transport channels. In addition, the partially freed Cs+ in the interlayer compensates for the vacancy of A-site cations during the perovskite preparation process. The In-aip(Cs) modified perovskite films have a flat morphology, large grains and excellent optoelectronic properties. Benefiting from the high-quality perovskite films and faster charge extraction, the In-aip(Cs)-modified PSCs achieved a champion PCE of 23.03%, superior to the In-aip-modified (22.29%) and control device (21.13%). More importantly, the unencapsulated PSCs modified with In-aip(Cs) exhibited outstanding humidity and thermal stability. Over a period of almost 1000 h, the unencapsulated In-aip(Cs)-modified device retained 85% of its initial PCE after storing in a glove box at 85℃, and retained 87% of the primary PCE upon storage in ambient condition at 25℃ under a humidity of 40%.