Stoichiometric Engineering of Cs2AgBiBr6 for Photomultiplication- Type Photodetectors

Photomultiplication (PM)-type photodetectors with a high external quantum efficiency (EQE) can be realized through adequately engineered trap states and trap-assisted charge injection. By strategically introducing slightly rich Bi and highly rich Br stoichiometric conditions, efficient trap states are realized for holes in lead-free Cs1.98AgBi1.15Br7.9 double perovskite (DP). With the diode structure of ITO/SnO2/Cs1.98AgBi1.15Br7.9/poly(3-hexylthiophene) (P3HT)/MoOx/Ag, where SnO2 and P3HT layers are used as the hole-and electron-blocking layers, respectively, successful realization of the selective hole trap and the resulting band bending/electron injection at the anode interface is demonstrated. As a result, a high EQE of similar to 16,000%, responsivity of similar to 50 A W-1, and specific detectivity of over 1012 Jones at -3 V are demonstrated. The origin of the suggested PM mechanism is discussed using photophysical and optoelectronic measurements and theoretical studies. This work ensures the successful demonstration of PM-type photodetectors using lead-free Cs2AgBiBr6 DP through strategic trap engineering.

Automated summary

PM-type photodetectors with high EQE can be achieved by engineering trap states and trap-assisted charge injection. The introduction of Bi and Br under specific stoichiometric conditions leads to efficient trap states for holes in lead-free Cs1.98AgBi1.15Br7.9 double perovskite. The diode structure ITO/SnO2/Cs1.98AgBi1.15Br7.9/P3HT/MoOx/Ag demonstrates successful realization of selective hole traps and resulting band bending/electron injection, resulting in high EQE, responsivity, and specific detectivity.