Crystallization regulation strategy by using 4,4'-cyclohexylidenebis(N, N-bis(p-tolyl)aniline) for high-performance air-processed perovskite photodetectors and solar cells

Abstract

Perovskites offer notable advantages, including simplified processing, reduced production costs, and scalability for large-area preparation. However, the crystallization process is very sensitive to humidity. Although some progress has been made in air-processed perovskite solar cells (PSCs), there remains a relative scarcity of research on air-processed perovskite photodetectors (PPDs). In this work, we propose a strategy employing electron-donating molecules to enhance the performance of both air-processed PPDs and PSCs. To promote the crystallization of perovskites in air and mitigate the trap states, 4,4'-cyclohexylidenebis(N, N-bis(p-tolyl)aniline) (TAPC), an electron-donating organic small molecule is added into the perovskite precursor to interact with Pb ions. The addition of TAPC not only reduces non-radiative recombination within the perovskite but also optimizes energy level alignment at the perovskite/C₆₀ interface. As a result, the TAPC-doped PSCs achieve a power conversion efficiency of 21.20 %. More importantly, for the PPDs, the doping of TAPC elevates the maximum external quantum efficiency to 95 %, while concurrently reducing the dark current density to 4.6 × 10⁻¹⁰ A cm⁻². With the suppressed dark current, the linear dynamic range of the PPD spans over 9 orders of magnitudes. Moreover, the response time and the operation stability are also significantly improved. Our crystallization regulation strategy using electron-donating molecules demonstrates its efficacy in enhancing the performance of both air-processed PPDs and PSCs, offering valuable insights for further advancements of perovskite devices fabricated in ambient conditions.