Surface defect passivation by 1,8-Naphthyridine for efficient and stable Formamidinium-based 2D/3D perovskite solar cells

Abstract

• 1,8-Naphthyridine (1,8-ND) as a modifier is implanted at the interface of PVK/HTL. • 1,8-ND reconstructs perovskite to fabricate efficient α-FAPbI 3 phase and 2D/3D PSCs. • 1,8-ND coordinate with Pb 2+ to passivate defects and construct quasi-2D perovskite. • 1,8-ND modified 2D/3D PSC achieved a champion PCE of 23.8% with excellent stability. The ionic properties of components determine that perovskite films will generate numerous charged surface defect under continuous high-temperature annealing, resulting in suboptimal performance and poor stability of perovskite solar cells (PSCs). Based on the principle of Lewis acid-base coordination, 1,8-naphthyridine (1,8-ND) with electron-rich structure was used to form complexes with Pb 2+ ions, and high-quality 2D/3D perovskite films with effective defect passivation were prepared by surface modification. Benefiting from suppressed nonradiative recombination, extended carrier lifetime, modified charge transport, improved hydrophobic properties and the optimized phase stability of α-FAPbI 3 , 1,8-ND modified 2D/3D PSCs with negligible hysteresis and satisfactory stability achieved a champion power conversion efficiency of 23.8% whose open circuit voltage was significantly improved from 1.09 V to 1.15 V, providing a resultful strategy to passivate surface defect while constructing 2D/3D perovskite.