Enhanced performance of perovskite solar cells via a bilateral electron-donating passivator as a molecule bridge

Abstract

Defects at the buried interface are the primary factors contributing to recombination losses and instability in perovskite solar cells (PSCs) with n–i–p structure. Here, a molecule with bilateral electron-donating groups, 6-amino-1-hexanol (HAL), is introduced between SnO₂ and perovskite (PVK) to optimize the characteristics of the buried interfacial properties, as well as the PVK film quality. The surface defects of SnO₂ can be more effectively passivated, and its energy level structure can be tuned more appropriately. Meanwhile, the electron-donating groups in HAL can passivate the Pb²⁺ defects and stabilize the [PbI₆]⁴⁻ octahedra at the buried interface. With the assistance of bilateral electron-donating groups, HAL can act as a molecular bridge to easily bridge SnO₂ and PVK to passivate the buried interfacial defects, thus enhancing device performance. As a result, the photovoltaic performance was significantly improved by the buried modification with HAL, ultimately achieving a champion PCE of 23.58%, far superior to the inferior PCE of 21.30% of the pristine device. Furthermore, after 35 days of storage at approximately 35% relative humidity (RH) and room temperature, the device based on HAL-modified SnO₂ demonstrates significantly better stability than the pristine device, as it still maintains over 90% of the initial efficiency. This study provides an effective molecular bridge strategy for further enhancing the performance of PSCs.