Directional Management Self-Additive Spacer Cations for Stable 2D Ruddlesden-Popper Perovskite Solar Cells with Efficiency over 21%

2D Ruddlesden-Popper perovskites are highly regarded materials for improving the stability of perovskite solar cells (PSCs). Wherein, self-additive 2D perovskites have recently been proposed to provide substantial strategies for managing the crystallization kinetics and bulk defects. For a profound understanding of the formation mechanisms, herein, with selecting three self-additive 2D perovskites as demonstrations, a comprehensive analysis of the self-additive behavior combing experimental and theoretical calculations is conducted. Self-additive 2D perovskites exhibit more suitable formation energies and strong interaction, which is conducive to realize the self-additive effect to form more stable structure. As demonstrated, glycine (Gly)-based spacer cations played a pivotal role in the nucleation and growth of 2D perovskites by adjusting the aggregation state of colloids precursor, resulting in excellent-quality films with large average grain size (approximate to 3 mu m). Meanwhile, theoretical analysis of electronic distribution and binding energies (Eb) revealed that glycine ethyl ester (Gly-E) perovskite possesses highly robust internal interactions, which will effectively mitigate defect formation and enhance device stability. Endowing with the above outstanding feature, Gly-E devices exhibited an optimized PCE of 21.60%, one of the highest PCEs among all 2D RP PSCs (n <= 6). The findings provide a basis for the rational design of self-additive 2D perovskites and achieving highly-performance 2D RP PSCs. By introducing self-additive spacer cation of glycine ethyl ester (Gly-E), the efficient and stable 2D PSCs with high film-quality are obtained. Gly-E exhibits suitable 2D formation energy to easily form 2D perovskite and better self-additive effect. Hence, the Gly-E 2D PSC (n = 6) display a champion PCE of 21.60%, which is one of the highest PCE among 2D PSCs with n <= 6. image