Passivation of perovskite surfaces using 2-hydroxyacetophenone to fabricate solar cells with over 20.7% efficiency under air environment

Abstract

As known, some defect states of perovskite film still seriously affect the efficiency and stability of perovskite solar cells (PSCs), and different passivation approaches have different passivation principles, areas, degrees and additional effects on perovskite films. Herein, in this contribution, we design a three-step optimization method including interface optimization and additive passivation strategies for enhancing the quality of perovskite films all-round, thereby increasing the power conversion efficiency (PCE) as well as enduring stability of PSCs which fabricated in atmospheric environment. We employ the L-aspartic acid (L-Asp) buffer layer which rich in amino acids, the cross-linking Sodium Glycinate (SG) additive with carboxylate and small amount of 2-Hydroxyacetophenone (2-HA) containing carbonyl groups to modify the bottom, inner and top parts of perovskite films, respectively. As a result, the passivated internal and surface defects of perovskite film could achieve an enlarged average grain size (500 nm) and display more defect-less, dense morphology. The strengthened interfacial charge transport ability can significantly improve the photovoltaic performance of devices. Consequently, the optimized PSC bring about the negligible hysteresis of photocurrent and a dramatic 20.71% PCE. Moreover, the temperature and moisture stability of optimized PSCs are both remarkably enhanced. The normalized PCE of un-encapsulated device which modified via 2-HA could still retain 80% of its original value after placed in the dark for 100 hours at 50% relative humidity and 85 °C, simultaneously. Overall, this simple and practical strategy supplies a hopeful channel to facilitate the commercialized PSCs.