Self‐Cleaning Perovskite Single Crystals Fabricated with Bis(trifluoromethylsulfonyl)imide Derived Ionic Liquid Toward High‐Performance Photodetection

Abstract Surface defects are crucial to perovskite single crystals (SCs) for versatile optoelectronic applications, whereas suffers from the intricate post‐treatments and unsatisfactory reproducibility within solution growth strategy due to the residue solvent corrosion and adsorbed precursors deposition. Here, an ionic liquid, 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (BMITFSI) is demonstrated, assisted solution growth approach for fabricating high‐quality self‐cleaning perovskite single crystals with no need for any post‐treatment. Benefiting from the in situ assembling in crystalline surface, BMITFSI can effectively decrease the crystallographic trap density by simultaneously introducing the self‐cleaning effect and optimizing the crystalline growth process. Particularly, as fabricated MAPbI 3 single crystal exhibits an impressive photodetection performance with a specific detectivity of 2.83 × 10 12 Jones in visible‐IR spectrum and a sensitivity of 7.24 × 10 4 µC Gy air −1 cm −2 in X‐ray detection, which is as good as the conventionally fabricated crystal with elaborate post‐treatments. Based on the chemical composition independent universality, this work paves an easy but efficient route to improve the current crystallization methodology toward high‐quality perovskite SCs fabrication.