Defect passivation of SnO2 doped with 2-FN for high-performance perovskite detectors

Tin dioxide (SnO2) is a widely used electron transport layer (ETL) in perovskite detectors, and optimizing the ETL is a common strategy to enhance detector performance. However, SnO2 films prepared via solution methods exhibit numerous defects, which degrade device performance. In this study, 2-fluoroethylamine hydrochloride (2-FN), containing both fluorine (F) and chlorine (Cl), was incorporated into SnO2 films. The incorporation of 2-FN effectively reduced oxygen vacancies in SnO2, passivated defects, and enhanced electrical conductivity. Additionally, the presence of 2-FN in the SnO2 film facilitated the growth and crystallization of the perovskite film, increased the size of perovskite grains, and improved crystallinity. Consequently, the external quantum efficiency (EQE) of the perovskite detector improved from 86.92% to 91.11%. Simultaneously, the dark current density decreased from 2.47 × 10−9 to 1.26 × 10−10 A cm−2, and the linear dynamic range (LDR) increased from 93.62 to 117.85 dB. The device stability was also enhanced due to the reduction of oxygen vacancies, with the 2-FN-doped perovskite detector maintaining 72.66% of its initial EQE after 32 days in a dark environment at 25 °C and 20–30% relative humidity.