Self-Assembled 1D/3D Perovskite Heterostructure for Stable All-Air-Processed Perovskite Solar Cells with Improved Open Circuit Voltage.

Abstract

Environmental unstability and photovoltage loss induced by defects are inevitable obstacles in all-air-processed perovskite solar cells (PSCs) development. In this study, the ionic liquid1-ethyl-3-methylimidazolium iodide ([EMIM]I) is introduced into the hole transport layer/three-dimensional (3D) perovskite interface to form a self-assembled 1D/3D perovskite heterostructure, which significantly reduces iodine vacancy defects and modulates band energy alignment, resulting in pronouncedly improved open-circuit voltage (Voc). As a result, the corresponding device exhibits the considerable power conversion efficiency with negligible hysteresis and a high Voc of 1.14 V. Most importantly, together with 1D perovskite superb stability, the remarkable high environmental and thermal stability of the 1D/3D PSC devices are achieved, which maintains 89% of unencapsulated device initial efficiency after 1320 h in air condition, and retains 85% of the initial efficiency when heated at 85 ℃for 22 h. This study affords an effective strategy to fabricate high-performance all-air-processed PSCs with outstanding stability.