Radiation Laboratory, †Department of Chemical and Biomolecular Engineering, and ‡Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556, United States.
ACS Nano. 2013 Sep 24;7(9):7967-74. doi: 10.1021/nn403058f. Epub 2013 Aug 20.
In solid-state semiconductor-sensitized solar cells, commonly known as extremely thin absorber (ETA) or solid-state quantum-dot-sensitized solar cells (QDSCs), transfer of photogenerated holes from the absorber species to the p-type hole conductor plays a critical role in the charge separation process. Using Sb2S3 (absorber) and CuSCN (hole conductor), we have constructed ETA solar cells exhibiting a power conversion efficiency of 3.3%. The hole transfer from excited Sb2S3 into CuSCN, which limits the overall power conversion efficiency of these solar cells, is now independently studied using transient absorption spectroscopy. In the Sb2S3 absorber layer, photogenerated holes are rapidly localized on the sulfur atoms of the crystal lattice, forming a sulfide radical (S(-•)) species. This trapped hole is transferred from the Sb2S3 absorber to the CuSCN hole conductor with an exponential time constant of 1680 ps. This process was monitored through the spectroscopic signal seen for the S(-•) species in Sb2S3, providing direct evidence for the hole transfer dynamics in ETA solar cells. Elucidation of the hole transfer mechanism from Sb2S3 to CuSCN represents a significant step toward understanding charge separation in Sb2S3 solar cells and provides insight into the design of new architectures for higher efficiency devices.
在固态半导体敏化太阳能电池中，通常称为极薄吸收体（ETA）或固态量子点敏化太阳能电池（QDSC），光生空穴从吸收体物种到 p 型空穴导体的转移在电荷分离过程中起着关键作用。我们使用 Sb2S3（吸收体）和 CuSCN（空穴导体）构建了 ETA 太阳能电池，其功率转换效率为 3.3%。从激发的 Sb2S3 到 CuSCN 的空穴转移限制了这些太阳能电池的整体功率转换效率，现在使用瞬态吸收光谱独立研究了这种转移。在 Sb2S3 吸收层中，光生空穴迅速定域在晶格的硫原子上，形成硫化物自由基（S(-•)）物种。这个被捕获的空穴从 Sb2S3 吸收体转移到 CuSCN 空穴导体，其指数时间常数为 1680 ps。通过 Sb2S3 中 S(-•)物种的光谱信号监测到这个过程，为 ETA 太阳能电池中的空穴转移动力学提供了直接证据。阐明从 Sb2S3 到 CuSCN 的空穴转移机制是理解 Sb2S3 太阳能电池中电荷分离的重要一步，并为设计更高效率器件的新架构提供了思路。
