Charge Traps in All-Inorganic CsPbBr3 Perovskite Nanowire Field-Effect Phototransistors

All-inorganic halide perovskite materials have recently emerged as outstanding materials for optoelectronic applications. However, although critical for developing novel technologies, the influence of charge traps on charge transport in all-inorganic systems still remains elusive. Here, the charge transport properties in cesium lead bromide, nanowire films are probed using a field-effect transistor geometry. Field-effect mobilities of mu(FET) = 4 x 10(-3) cm(-2) V-1 s(-1) and photoresponsivities in the range of R = 25 A W-1 are demonstrated. Furthermore, charge transport both with and without illumination is investigated down to cryogenic temperatures. Without illumination, deep traps dominate transport and the mobility freezes out at low temperatures. Despite the presence of deep traps, when illuminating the sample, the field-effect mobility increases by several orders of magnitude and even phonon-limited transport characteristics are visible. This can be seen as an extension to the notion of defect tolerance of perovskite materials that has solely been associated with shallow traps. These findings provide further insight in understanding charge transport in perovskite materials and underlines that managing deep traps can open up a route to optimizing optoelectronic devices such as solar cells or phototransistors operable also at low light intensities.

Automated summary

This study investigates the charge transport properties in cesium lead bromide nanowire films, revealing that despite the presence of deep traps, the field-effect mobility increases significantly when the sample is illuminated, showing phonon-limited transport characteristics. The findings suggest that managing deep traps could lead to optimizing optoelectronic devices such as solar cells even at low light intensities.