Impact of Absorber Layer Morphology on Photovoltaic Properties in Solution-Processed Chalcopyrite Solar Cells.

Solution-processed chalcopyrite solar cells can be economically produced on a large scale; however, for them to be commercially viable, their low efficiency and detrimental processing have to be overcome. To this end, extensive research efforts have been devoted to boost device efficiency and develop benign solution processes. In this review, relevant processes are categorized into molecular-based and particulate-based solution processes, and progress is evaluated in terms of device performance and processing. To identify strategies for improving device performance, the key parameters affecting the optoelectronic properties of the device are discussed. Interestingly, the authors found an unnoticed fact from previously reported experimental results in literature: short-circuit current density increases and deficit of open-circuit voltage decreases as the average domain size of the absorber layer increases. In addition, the power conversion efficiency increases with the grain size irrespective of the band gap, thickness, and processing conditions. Ensuring a large grain size is specifically elucidated to be necessary to increase the photocurrent generation and reduce the charge carrier recombination in the chalcopyrite solar cells. The findings and related reviews afford critical insight into the absorber film design to improve the performance of solution-processed chalcopyrite solar cells.