Perovskite Bifunctional Diode with High Photovoltaic and Electroluminescent Performance by Holistic Defect Passivation.

Integration of photovoltaic (PV) and electroluminescent (EL) functions and/or units in one device is attractive for new generation optoelectronic devices but it is challenging to achieve highly comprehensive efficiency. Herein, perovskite solar cells (PSCs) are fabricated, assisted by 3-sulfopropyl methacrylate potassium salt (SPM) additive to tackle this issue. SPMs not only induce large grain size during the film formation but also produce a secondary phase of 2D K2 PbI4 to passivate the grain boundaries (GBs). In addition, its sulfonic acid group and potassium ion can coordinate to lead ion and fill the interstitial defects, respectively. Thus, SPM reduces the defective states and suppresses nonradiative recombination loss. As a result, planar PSC delivers a power conversion efficiency of ≈22%, with a maximum open-circuit voltage (Voc ) of 1.20 V. The Voc is 94% of the radiative Voc limit (1.28 V), higher than the control device (Voc of 1.12 V). In addition, the reciprocity between PV and EL is also correlated to quantify the energy losses and understand the device physics. When operated as a light-emitting diode, the maximum EL external quantum efficiency (EQEEL ) is up to 12.2% (EQEEL of 10.7% under an injection current of short-circuit photocurrent), thus leading to high-performance PV/EL dual functions.