TiO2has been widely used as an n-type overlayer, simultaneously serving as a protective layer for photocathodes. However, the photovoltage generated from a TiO2junction with p-type absorbers, such as p-Si, Sb2Se3, SnS, and Cu2O, is insufficient. We report a dipole reorientation strategy to overcome this limitation by inserting a polyethylenimine ethoxylated (PEIE) layer between a p-type absorber and TiO2. Furthermore, we demonstrate that the PEIE dipole orientation can be rearranged by increasing the layer thickness, leading to an upward shift of the TiO2band edge. The magnitude of band shift induced by the dipole effect depends on the TiO2layer thickness. Using this approach, the onset potential was significantly improved to 0.5 V versus the reversible hydrogen electrode (VRHE) in a p-Si/PEIE/TiO2/Pt device. The versatility of the effective dipole reorientation strategy was demonstrated by application to a range of TiO2-protected heterojunction photocathodes based on Sb2Se3, Cu2O, and SnS.
Bibliographical noteFunding Information:
This research was supported by the National R&D Program through the National Research Foundation of Korea (NRF), funded by the Ministry of Science and ICT (No. 2021R1A3B1068920 and 2021M3H4A1A03049662). This research was also supported by the Yonsei Signature Research Cluster Program of 2021 (2021-22-0002).
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All Science Journal Classification (ASJC) codes
- Chemistry (miscellaneous)
- Renewable Energy, Sustainability and the Environment
- Fuel Technology
- Energy Engineering and Power Technology
- Materials Chemistry