Controlling the Decomposition of Hybrid Perovskite by a Dithienopyrrole-Based Hole Transport Layer toward Thermostable Solar Cells

Due to the amorphous nature and overly low carrier density of intrinsic organic semiconductors, doping either by accident or on purpose is a feasible strategy to achieve sufficiently high carrier density as well as charge mobility. We herein design and synthesize a structurally simple dithienopyrrole-based molecular semiconductor. Mixed with the thermally stable acid salt 4-tert-butylpyridinium bis(trifluoromethanesulfonyl)imide, the resultant air-doped composite presents a hole density of 2.4 × 1018 cm–3, a hole mobility of 9.3 × 10–4 cm2 V–1 s–1, an electrical conductivity in excess of 100 μS cm–1, and, in particular, a glass transition temperature of 110 °C as well as low gas permeation coefficients. These critical quality factors allow us to fabricate perovskite solar cells with 21.8% efficiency at the AM1.5G conditions, which also maintain 86% of the initial efficiency after 1000 h of aging at 85 °C.