Room-temperature growth of perovskite single crystals via antisolvent-assisted confinement for high-performance electroluminescent devices

Organic-inorganic halide perovskite single crystals (OIHP-SCs) are promising light-emitting materials for bright electroluminescence (EL) devices due to their superior optoelectronic properties and excellent stability. However, the conventional high-temperature growth methods will inevitably disturb the ordered growth and introduce massive defects in OIHP-SCs, leading to the degradation of device performance. The preparation of thin OIHP-SCs with low trap-state densities for high-performance EL devices remains a formidable challenge. Here, we develop an efficient antisolvent-assisted confined growth (AACG) method for the room-temperature growth of formamidinium lead bromide (FAPbBr 3 ) perovskite SCs. An antisolvent vapour environment is intentionally introduced in the spatially confined growth process to lower the free energy barrier for nucleation, enabling the growth of high-quality FAPbBr 3 SCs at room temperature. Consequently, FAPbBr 3 SCs with ultralow trap-state density of 2.15 × 10 9 cm −3 and amplified spontaneous emission (ASE) threshold of 7.1 µJ cm −2 could be achieved, representing the best results ever reported for FAPbBr 3 SCs. By leveraging the high crystal quality of FAPbBr 3 SCs, SC-based perovskite light-emitting diodes (PeLEDs) with a high luminance of over 26,000 cd m −2 and a peak current efficiency (CE) of 13.02 cd A −1 are demonstrated. Our work opens up new opportunities for the development of high-performance EL devices based on OIHP-SCs.