Organolead halide perovskites have attracted substantial attention due to
their excellent physical properties, which enable them to serve as the active
material in emerging hybrid solid-state solar cells. Here we investigate the
phototransistors based on hybrid perovskite films, and provide direct evidence
for their superior carrier transport property with ambipolar characteristics.
The field-effect mobilities for triiodide perovskites at room temperature are
measured as 0.18 (0.17) cm2 V-1 s-1 for holes (electrons), which increase to
1.24 (1.01) cm2 V-1 s-1 for mixed halide perovskites. The photoresponsivity of
our hybrid perovskite devices reaches 320 A W-1, which is among the largest
values reported for phototransistors. Importantly, the phototransistors exhibit
an ultrafast photoresponse speed of less than 10 {\mu}s. The solution-based
process and excellent device performance strongly underscore hybrid perovskites
as promising material candidates for photoelectronic applications
