DOI: 10.1002/adfm.202400806 ISSN: 1616-301X

Conjugated Polythiophene Frameworks as a Hole‐Selective Layer on Ta3N5 Photoanode for High‐Performance Solar Water Oxidation

Jin Wook Yang, Hee Ryeong Kwon, Su Geun Ji, Jaehyun Kim, Sol A Lee, Tae Hyung Lee, Sungkyun Choi, Woo Seok Cheon, Younhwa Kim, Jungwon Park, Jin Young Kim, Ho Won Jang
  • Electrochemistry
  • Condensed Matter Physics
  • Biomaterials
  • Electronic, Optical and Magnetic Materials
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Abstract

Discovering a competent charge transport layer promoting charge separation in photoelectrodes is a perpetual pursuit in photoelectrochemical (PEC) water splitting to achieve high solar‐to‐hydrogen (STH) conversion efficiency. Here, a conjugated polythiophene framework (CPF‐TTB) on Ta3N5 is elaborately electropolymerized, substantiating the hole transport behavior in their heterojunction. Tailored band structures of the CPF‐TTB/Ta3N5 reinforce the separation of photogenerated carriers, elevating a fill factor of the photoanode modified with a cocatalyst. The enhanced hole extraction enables the NiFeOx/CPF‐TTB/Ta3N5/TiN photoanode to generate a remarkable water oxidation photocurrent density of 9.12 mA cm−2 at 1.23 V versus the reversible hydrogen electrode. A tandem device combining the photoanode with a perovskite/Si solar cell implements an unbiased solar water splitting with a STH conversion efficiency of 6.26% under parallel illumination mode. This study provides novel strategies in interface engineering for metal nitride‐based photoelectrodes, suggesting a promise of the organic–inorganic hybrid photoelectrode for high‐efficiency PEC water splitting.

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