Enhanced stability and ultraviolet photodetection performance in CsPbBr 3 nanoplatelets via FA doping

Abstract

Quantum-confined CsPbBr3 nanoplatelets (NPLs) are appealing candidates for ultraviolet (UV)/blue photodetectors due to their strong excitonic binding energy and large absorption coefficient. However, the inherent soft lattice and surface defects of CsPbBr3 NPLs lead to poor operational stability, limiting their practical applications. Here, we report an A-site alloying strategy that enhances the structural rigidity and defect formation energy of CsPbBr3 NPLs. The strategy synergistically employs short-chain tetrolic acid (TLA) ligands to passivate uncoordinated Pb2+ ions and formamidinium (FA+) cations to compensate for Cs+ vacancies. This dual repair strategy enhanced both the conductivity and UV irradiation stability of CsPbBr3-based NPLs. As a result, the self-powered UV photodetectors based on Cs0.73FA0.27PbBr3-TLA NPLs exhibited a responsivity of 89 mA W-1, a specific detectivity of 3.99 × 1012 Jones, and an on/off ratio approaching 106 at 0 V bias. Even after 30 days of ambient storage, the device maintained excellent photoresponse and a high specific detectivity of 1.73 × 1012 Jones. Clear images obtained with a custom-built 2D imaging system corroborate the fast response and excellent stability of the device. These results underscore the efficacy of the combined lattice and surface engineering approach for realizing high-performance, durable perovskite NPL-based UV photodetectors.