Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu, 610054, China.
Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-8656, Japan.
Nat Commun. 2022 Dec 15;13(1):7769. doi: 10.1038/s41467-022-35538-1.
The trade-off between light absorption and carrier transport in semiconductor thin film photoelectrodes is a major limiting factor of their solar-to-hydrogen efficiency for photoelectrochemical water splitting. Herein, we develop a heterogeneous doping strategy that combines surface doping with bulk gradient doping to decouple light absorption and carrier transport in a thin film photoelectrode. Taking La and Mg doped TaN thin film photoanode as an example, enhanced light absorption is achieved by surface La doping through alleviating anisotropic optical absorption, while efficient carrier transport in the bulk is maintained by the gradient band structure induced by gradient Mg doping. Moreover, the homojunction formed between the La-doped layer and the gradient Mg-doped layer further promotes charge separation. As a result, the heterogeneously doped photoanode yields a half-cell solar-to-hydrogen conversion efficiency of 4.07%, which establishes TaN as a leading performer among visible-light-responsive photoanodes. The heterogeneous doping strategy could be extended to other semiconductor thin film light absorbers to break performance trade-offs by decoupling light absorption and carrier transport.
半导体薄膜光电化学水分解的光电效率受光吸收和载流子输运之间的权衡限制。在此，我们开发了一种异质掺杂策略，将表面掺杂与体梯度掺杂相结合，以解耦薄膜光电化学水分解的光吸收和载流子输运。以 La 和 Mg 共掺杂 TaN 薄膜光电阳极为例，通过减轻各向异性光吸收实现表面 La 掺杂来增强光吸收，而梯度 Mg 掺杂诱导的梯度能带结构则保持了体相中的有效载流子输运。此外，La 掺杂层和梯度 Mg 掺杂层之间形成的同质结进一步促进了电荷分离。结果，异质掺杂光电阳极的半电池太阳能到氢气的转化效率为 4.07%，这使得 TaN 在可见光响应光电阳极中表现出色。该异质掺杂策略可扩展到其他半导体薄膜光吸收体，通过解耦光吸收和载流子输运来打破性能权衡。
