A conjugated Donor-acceptor blend passivation interlayer for the high-performance carbon-based perovskite solar cells

Abstract

The interfacial properties between perovskite active layer and carbon electrode significantly affects the energy conversion efficiency and stability of carbon-based perovskite solar cells. In this work a conjugated Donor-Acceptor blend with a dendrite shaped copper phthalocyanine derivative 8TPAEPC as a donor (D) and Y6 as a typical acceptor (A) was designed to enhance the carrier extraction across the perovskite/carbon interface. The respective D and A molecules form strong interactions with I− and Pb2+ on the surface of perovskite by rich functional group atoms, which can synergistically passivate the non-radiative defects. Moreover, the dipoles from D-A coupling construct a strong internal built-in electric field for further suppression of the unwanted recomination. Compared with 8TPAEPC, 8TPAEPC-Y6 blend exhibits the faster charge interface transfer dynamics. Consequently, Carbon-based perovskite solar cells (C–PSCs) optimized by 8TPAEPC-Y6 achieve champion power conversion efficiency (PCE) of 17.07%, superior to those with 8TPAEPC (16.08%), Y6 (15.68%) and pristine perovskite (14.06%). Meanwhile, the C–PSCs with the hydrophobic 8TPAEPC-Y6 blend greatly improved moisture long-term stability that over 90% PCE could remain as long as 90 days. This work finds out an innovative D-A blend interfacial solution for achieving highly efficient and stable C–PSCs.