Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes.
Limitation of Fermi level shifts by polaron defect states in hematite photoelectrodes.
复制标题
在赤铁矿光电极中极性缺陷状态的费米水平偏移的局限性。
DOI：
10.1038/s41467-018-06838-2
复制
发表时间：
2018-10-17
影响因子：
16.6
通讯作者：
Jaegermann W
中科院分区：
文献类型：
--
作者：
Lohaus C;Klein A;Jaegermann W
光学带隙是光催化水分解吸收剂的主要选择标准。由于它的理想价值，人们对赤铁矿进行了大量的研究，但没有达到预期的效果。本文研究了赤铁矿中掺杂和接触形成的费米能级位置。在价带最大值以上1.8 eV处，由于极化子的形成，确定了费米能级位置的上边界。这导致了赤铁矿有效带隙的不同概念，我们认为这可以转移到光激发后具有竞争性极化子形成的任何材料：2.2 eV的光学带隙偏离1.75 eV的有效电子带隙。极化子态在（准）费米能级位移中起限制作用，限制了电荷转移反应的电位。此外，它还导致了电化学接触中赤铁矿带边缘位置的不正确测定。赤铁矿由于其稳定性和良好的光学带隙，被认为是一种合适的水裂解光催化剂，但其性能尚未达到理论预期。在这里，作者表明这是由于隙内极化态减少了有效电子带隙。
The optical band gap is a major selection criterion for an absorber in photocatalytic water splitting. Due to its ideal value hematite has been intensively investigated without reaching the expectation, yet. In this work, the Fermi level positions in hematite due to doping and contact formation are investigated. An upper boundary for the Fermi level position at 1.8 eV above the valence band maximum due to the formation of polarons is identified. This results in a different concept of the effective band gap for hematite which we believe is transferable to any material with competing polaron formation after optical excitation: the optical band gap of 2.2 eV deviates from an effective electronic band gap of 1.75 eV. The polaron state acts as a limit in (quasi-)Fermi level shift, restricting the potential of charge transfer reactions. Additionally, it has led to an incorrect determination of the band edge positions of hematite in electrochemical contacts. Hematite has been proposed as a suitable photocatalyst for water splitting based on its stability and appealing optical band gap, but its performance has not reached theoretical expectations. Here the authors show that this is due to intra-gap polaronic states that reduce the effective electronic band gap.
登录
查看更多内容
通过氧化铁和硅实现无辅助太阳能分解水
影响因子：
16.6
作者：
Jang, Ji-Wook;Du, Chun;Ye, Yifan;Lin, Yongjing;Yao, Xiahui;Thorne, James;Liu, Erik;McMahon, Gregory;Zhu, Junfa;Javey, Ali;Guo, Jinghua;Wang, Dunwei
通讯作者：
Wang, Dunwei
影响因子：
41.2
作者：
Carneiro, Lucas M.;Cushing, Scott K.;Leone, Stephen R.
通讯作者：
Leone, Stephen R.
影响因子：
3.9
作者：
Klein, Andreas
通讯作者：
Klein, Andreas
影响因子：
16.6
作者：
Li, Jiangtian;Cushing, Scott K.;Wu, Nianqiang
通讯作者：
Wu, Nianqiang
影响因子：
2.9
作者：
Braun, Artur;Chen, Qianli;Zhu, Junfa
通讯作者：
Zhu, Junfa