Layer-by-layered organic solar cells: Morphology optimizing strategies and processing techniques

The last decades have witnessed the rapid development and the gradually improved efficiencies of organic solar cells (OSCs), which show great potentials in the fabrication of eco-friendly and flexible photovoltaic panels. Layer-by-layered (LBL) structure via sequential processing of the donor and acceptor layers becomes an advisable option to construct pseudo-bilayer configurations in OSC active layer. Favorable vertical phase separation and sufficient exciton dissociation interfaces can be simultaneously realized in such aggregation morphology via different processing technologies and strategies. High efficiencies of over 18% in ternary LBL device and 11.9% in LBL-processed module (11.52 cm(2)) have been successfully achieved in recent works. Moreover, the unique merits of LBL structure in individual layer processing enable it a promising candidate for large-scale printing and further industrialization of OSCs. This perspective provides the recent advance of LBL OSCs with the focus on fabrication technologies and strategies for morphology control and also proposes the current thinking and perspective on LBL structures for future development.