Yang Wooseok, Lee Seungmin, Kwon Hyeok-Chan, Tan Jeiwan, Lee Hyungsoo, Park Jaemin, Oh Yunjung, Choi Hyunyong, Moon Jooho
ACS Nano. 2018 Nov 27;12(11):11088-11097. doi: 10.1021/acsnano.8b05446. Epub 2018 Oct 29.
Solar-energy conversion by photoelectrochemical (PEC) devices is driven by the separation and transfer of photogenerated charge carriers. Thus, understanding carrier dynamics in a PEC device is essential to realizing efficient solar-energy conversion. Here, we investigate time-resolved carrier dynamics in emerging low-cost SbSe nanostructure photocathodes for PEC water splitting. Using terahertz spectroscopy, we observed an initial mobility loss within tens of picoseconds due to carrier localization and attributed the origin of carrier localization to the rich surface of SbSe nanostructures. In addition, a possible recombination at the interface between SbSe and the back contact is elucidated by time-resolved photoluminescence analysis. We also demonstrated the dual role of the RuO co-catalyst in reducing surface recombination and enhancing charge transfer in full devices using intensity-modulated spectroscopy. The relatively low onset potential of the SbSe photocathode is attributed to the sluggish charge transfer at a low applied bias rather than to fast surface recombination. We believe that our insights on carrier dynamics would be an important step toward achieving highly efficient SbSe photocathodes.
光电化学（PEC）装置的太阳能转换是由光生电荷载流子的分离和转移驱动的。因此，了解PEC装置中的载流子动力学对于实现高效太阳能转换至关重要。在此，我们研究了用于PEC水分解的新型低成本SbSe纳米结构光阴极中的时间分辨载流子动力学。使用太赫兹光谱，我们观察到由于载流子局域化，在几十皮秒内出现了初始迁移率损失，并将载流子局域化的起源归因于SbSe纳米结构丰富的表面。此外，通过时间分辨光致发光分析阐明了SbSe与背接触之间界面处可能的复合。我们还使用强度调制光谱证明了RuO助催化剂在降低全器件表面复合和增强电荷转移方面的双重作用。SbSe光阴极相对较低的起始电位归因于低施加偏压下缓慢的电荷转移，而不是快速的表面复合。我们相信，我们对载流子动力学的见解将是朝着实现高效SbSe光阴极迈出的重要一步。
