Highly efficient and stable near-infrared photodetectors enabled from passivated tin–lead hybrid perovskites

Abstract

Tin–lead perovskite-based photodetectors have a wide light-absorption wavelength range, which spans 1000 nm. However, the preparation of the mixed tin-lead perovskite films faces two great obstacles, namely easy oxidation of Sn2+ to Sn4+ and fast crystallization from tin-lead perovskite precursor solutions, thus further resulting in poor morphology and high density of defects in tin-lead perovskite films. In this study, we demonstrated a high-performance of near-infrared photodetectors prepared from a stable low-bandgap (MAPbI3)0.5(FASnI3)0.5 film modified with 2-fluorophenethylammonium iodide (2-F-PEAI). The addition engineering can efficiently improve the crystallization of (MAPbI3)0.5(FASnI3)0.5 films through the coordination binding between Pb2+ and N atom in 2-F-PEAI, and resulting in a uniform and dense (MAPbI3)0.5(FASnI3)0.5 film. Moreover, 2-F-PEAI suppressed Sn2+ oxidation and effectively passivated defects in the (MAPbI3)0.5(FASnI3)0.5 film, thereby significantly reducing the dark current in the PDs. Consequently, the near-infrared photodetectors showed a high responsivity with a specific detectivity of over 1012 Jones at 800 to near-1000 nm. Additionally, the stability of PDs incorporated with 2-F-PEAI has been significantly improved under air conditions, and the device with the 2-F-PEAI ratio of 400:1 retained 80% of its initial efficiency after 450 h storage in air without encapsulation. Finally, 5 × 5 cm2 photodetector arrays were fabricated to demonstrate the potential utility of the Sn–Pb perovskite photodetector in optical imaging and optoelectronic applications.

Emerging Opportunities in Lead-Free and Lead–Tin Perovskites for Environmentally Viable Photodetector Applications

“…Consequently, defects are another source of charge recombination, in addition to Sn vacancies. Different additives in Table , such as organic compounds, metal–organic frameworks (MOFs), bulky organic ammonium salts, ,,, and inorganic compounds, have been applied as passivating agents of the defects and as retarders of Sn oxidation in Sn–Pb perovskites.…”

“…The device with DS passivation exhibited a low dark current of 1.25 × 10 −6 A/cm 2 at −0.1 V. The optimized Sn−Pb perovskite photodetectors demonstrated a high EQE close to 80% from 300 to 1050 nm, a low 1/f noise of 5.36 × 10 −13 A/Hz 1/2 at 70 Hz, and an ultrafast response speed of 35 ns. A halogenated derivative of PEA, 2F-PEA (2-fluorophenylethylammonium), has shown great success in the passivation of defects and the suppression of tin oxidation 135. A high responsivity of 0.41 AW −1 with a specific detectivity of over 10 12 Jones at the range of 800−1000 nm were the output of the device with 2F-PEA.…”