Low-cost materials for organic solar cells

Solution processible organic solar cells (OSCs) have attracted much attention as one of the most promising candidates for sustainable energy techniques over the past two decades. So far, the power conversion efficiency (PCE) of OSCs has reached over 18% and increasingly closed the gap with inorganic and hybrid solar cells, which exceeds the requirement in efficiency towards commercial application. Low cost is generally labeled as one of the potential advantages of OSCs, compared with other photovoltaic technologies. However, currently most of the high-performance materials need tedious synthetic steps and/or suffer from relatively high cost. In addition, halogenated solvents which are highly toxic and expensive are widely used during processing; besides, they are not environmentally friendly, which would bring about extra expense for management and disposal. Thus, the development of low-cost high-performance materials, and cheap and “green” processing for OSCs is the imperative and urgent issue to be solved towards industrial-scale production. In this review, we summarize the recent advances in low-cost materials and eco-friendly processing for OSCs from the aspects of the synthetic method, photoactive materials, interfacial materials and processing solution. We hope that this review affords an overview and deep understanding of low-cost materials and processing solutions for OSCs. Finally, we will provide our perspectives on possible directions and challenges to further reduce the material cost of OSCs.