High detectivity and linear dynamic range in green light perovskite quantum dot photodetectors via surface passivation

• Surface passivation of green emitting FAPbBr₃ QDs with DDAB optimized the QPD's performance. • Passivation replaced short-chain ligands, improving both structural stability and optoelectronic properties. • The device configuration (ITO/PCBM/FAPbBr₃-DDAB/TAPC/MoO 3 /Ag) with PCBM as the ETL, achieved an EQE) of 26.94 %. • D* of the device increased to 7.93 × 10 12 Jones, and transient photovoltage rise and fall times reduced to 3.64 μs and 1.97 μs, respectively. Perovskite quantum dots photodetectors (QPDs) are acclaimed for their exceptional sensitivity and responsivity across a wide spectral range. The low-cost fabrication of QPDs enables the development of multifunctional, high-performance optoelectronic devices with fewer defects, enhanced carrier mobility, and improved stability, leading to superior conversion efficiency. However, green-light-emitting FAPbBr₃ perovskites, in particular, remain relatively underexplored in the literature. In this study, we focused on synthesis of FAPbBr₃ green-light QPDs, utilizing didodecyldimethylammonium bromide (DDAB) ligands for the surface passivation. The DDA⁺ ion exhibits a stronger affinity for the negatively charged Br⁻ sites, and its shorter chain enhances effective surface passivation of the QDs, while also facilitating the transfer of photoexcited charges within the FAPbBr₃ QDs. The device (ITO/PCBM/FAPbBr₃-DDAB/TAPC/MoO 3 /Ag) incorporating [6 % at 530 nm and a detectivity of 7.93 × 10¹² Jones. Further, the performance of the FAPbBr 3 photodetector was significantly enhanced, leading to an increase in a Detectivity (D*) to 7.93 × 10 12 Jones, a linear dynamic range (LDR) of 103.33 dB and on/off response time of 3.64 μs and 1.97 μs, respectively.