Stable block copolymer single-material organic solar cells: progress and perspective

The rapidly increasing population and decreasing supply of fossil fuels have resulted in a growing demand for energy, which has brought on an energy crisis. Accordingly, harvesting renewable and clean solar energy has been demonstrated as an effective approach to solve this critical issue. Among the various photovoltaic (PV) technologies, solution-processable organic solar cells (OSCs) have attracted worldwide interest as inexpensive renewable power sources. This promising technology is favored due to its advantages including low-cost, lightweight, and potential for large-area device fabrication on flexible substrates through roll-to-roll techniques. In the last five years, the power-conversion efficiencies (PCEs) of organic solar cells have rapidly increased from 10% to nearly 20%. However, despite this rapid progress, complicated procedures are required for the preparation of the photoactive layer and the long-term stability of the current OSCs still requires further research and development. In this case, through rational synthetic protocols, block copolymers (BCPs) effectively connect organic segments, further minimizing the procedures for preparing ready-to-coat organic conductive inks and significantly enhancing the morphological stability. Consequently, the study of single-material OSCs based on BCPs has led to enhanced stability and a deeper understanding of the active layer. In this review article, we show how the development of functional organic BCP semiconductors has gained prominence for single-material OSCs, the rapid progress in efficiency to over 15%, and finally the next steps in BCP design, processing, and device architecture to further provide a suitable platform for accelerating OSCs to solve the big energy challenges.