Nano-graphdiyne derivative and natural amino acid molecule as bilateral charge transport layer dopants for efficient perovskite solar cells

Abstract

The defective interfaces between the perovskite and charge transport layers are detrimental to the photovoltaic performance and operational stability of n–i–p structured perovskite solar cells (PSCs). In this work, a wheel-like nano-graphdiyne derivative o-TB-GDY and natural amino acid molecule serine were doped into the Spiro-OMeTAD hole transport layer (HTL) and SnO₂ electron transport layer (ETL), respectively. On the one hand, the highly π-conjugated o-TB-GDY formed strong coordination bonds with the uncoordinated Pb²⁺ ions on the top surface of the perovskite film. On the other hand, the serine molecule not only effectively passivated the uncoordinated Sn and O vacancies defects of the SnO₂ film but also chelated with the uncoordinated Pb²⁺ ions on the buried surface of the perovskite film. Consequently, the deleterious defects within the SnO₂ film, at both the top (perovskite/spiro-OMeTAD) and buried (SnO₂/perovskite) interfaces, were concurrently reduced, thereby leading to suppressed non-radiative recombination and optimized energy level alignment. As a result, the champion PSCs based on the dual-doping strategy achieved an efficiency of 24.46% compared to that (22.50%) of the control device, and a high open-circuit voltage exceeding 1.22 V. Additionally, the unencapsulated target devices exhibited excellent long-term operational and thermal stability.