5 research outputs found
Direct Time Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4
BiVO<sub>4</sub> is a promising photoanode
candidate for water
splitting applications, but its microscopic charge carrier transport
properties are not yet fully understood. We investigated the photoinduced
carrier mobility for undoped and 1% tungsten-doped BiVO<sub>4</sub> thin films in an early time window from 1 ps to 1 ns using THz spectroscopy.
The combined electron–hole effective mobility gradually decreases
with time by 1 order of magnitude starting at an upper limit of ∼0.4
cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup>. The loss
is attributed to carrier localization. We provide for the first time
direct time-resolved evidence of hole polaron formation accompanied
by the temporal buildup of a polaron population in parallel to initial
carrier trapping. A mobility of 0.02 cm<sup>2</sup> V<sup>–1</sup> s<sup>–1</sup> is found for the self-trapped carriers, which
leads to a thermal hopping activation energy of ∼90 meV