Toward Efficient Charge Collection and Light Absorption: A Perspective of Light Trapping for Advanced Photoelectrodes

Sun light driven water splitting is a promising method to produce hydrogen in a clean and sustainable way. The photoelectrochemical (PEC) cell is highly desirable among various solar water splitting techniques as it is potentially robust, cost-effective, and durable. However, arguably the biggest problem to date for sustainable photoelectrodes currently under intensive study is that the carrier diffusion length is always much shorter than the optical length, thus seriously limiting the cell’s power conversion efficiency. Light trapping strategies could enable multiple passes of light through the absorber to enhance the absorption while still keeping the absorber thickness below the transport limitation. Herein we briefly review recent developments of light management strategies in PEC electrodes by focusing on the relevant concepts, materials, and structures. In addition, current shortcomings and outlooks will be discussed in the hope that more attention of the research community will be drawn to this promising field.