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

Quantum-confined CsPbBr 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 CsPbBr 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 CsPbBr NPLs. The strategy synergistically employs short-chain tetrolic acid (TLA) ligands to passivate uncoordinated Pb ions and formamidinium (FA) cations to compensate for Cs vacancies. This dual repair strategy enhanced both the conductivity and UV irradiation stability of CsPbBr-based NPLs. As a result, the self-powered UV photodetectors based on CsFAPbBr-TLA NPLs exhibited a responsivity of 89 mA W, a specific detectivity of 3.99 × 10 Jones, and an on/off ratio approaching 10 at 0 V bias. Even after 30 days of ambient storage, the device maintained excellent photoresponse and a high specific detectivity of 1.73 × 10 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.