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

Abstract 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 K₂PbI₄ 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 (V_oc) of 1.20 V. The V_oc is 94% of the radiative V_oc limit (1.28 V), higher than the control device (V_oc 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 (EQE_EL) is up to 12.2% (EQE_EL of 10.7% under an injection current of short‐circuit photocurrent), thus leading to high‐performance PV/EL dual functions.