Asymmetric alkyl diamine based Dion–Jacobson low-dimensional perovskite solar cells with efficiency exceeding 15%

Abstract

Low-dimensional (LD) Dion–Jacobson perovskites (DJPs) are showing great potential to solve the stability issue of perovskite solar cells (PSCs). However, it is still a challenge to simultaneously obtain high power conversion efficiency (PCE) and high stability in DJP-LD-PSCs. Here, we present an asymmetric alkyl diammonium 3-(dimethylammonium)-1-propylammonium (DMAPA²⁺) as a spacer cation to resolve this issue. With the small adjacent inorganic interlayer distance, PSCs based on LD (DMAPA)MA_n−1Pb_nI_3n+1 (n = 1) achieve a PCE of 3.85%, the currently highest PCE for PSCs based on n = 1 LD-DJPs. The systematic study of the crystallization kinetics of DJPs with higher n values (n = 3, 4, 5) demonstrates that the perovskite quality is mainly dominated by the formation and decomposition of their intermediate phase. PSCs based on n = 4 LD-DJP (DMAPA)MA₃Pb₄I₁₃, with vertical crystal orientation, hierarchical phase distribution and low trap density, yield high PCEs up to 15.16%, and excellent stability with over 90% of the initial PCE retained without encapsulation after being stored at 85 °C in air for 1000 hours and ∼80% PCE retained after 300 h of continuous operation under 1-sun illumination in air.