Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4
Direct Time-Resolved Observation of Carrier Trapping and Polaron Conductivity in BiVO4
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DOI：
10.1021/acsenergylett.6b00423
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发表时间：
2016-10
影响因子：
22
通讯作者：
Manuel Ziwritsch;Sönke Müller;H. Hempel;T. Unold;F. Abdi;R. Krol;D. Friedrich;R. Eichberger
中科院分区：
文献类型：
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作者：
Manuel Ziwritsch;Sönke Müller;H. Hempel;T. Unold;F. Abdi;R. Krol;D. Friedrich;R. Eichberger
BiVO4 是一种很有前景的光阳极候选材料，可用于水分解应用，但其微观载流子传输特性尚未完全了解。我们使用太赫兹光谱研究了未掺杂和 1% 钨掺杂 BiVO4 薄膜在 1 ps 至 1 ns 的早期时间窗口内的光致载流子迁移率。组合的电子-空穴有效迁移率随着时间的推移逐渐降低 1 个数量级，上限为 ∼0.4 cm2 V-1 s-1。损失归因于运营商本地化。我们首次提供了空穴极化子形成的直接时间分辨证据，以及与初始载流子捕获平行的极化子群体的时间积累。自捕获载流子的迁移率为 0.02 cm2 V–1 s–1，这导致热跳跃激活能约为 90 meV。
BiVO4 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 BiVO4 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 cm2 V–1 s–1. 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 cm2 V–1 s–1 is found for the self-trapped carriers, which leads to a thermal hopping activation energy of ∼90 meV.