Molecular Design and Synthesis of Semiconducting Conjugated Polymers Based on Diketopyrrolopyrrole forHigh Performance Polymer Solar Cells

Abstract

Polymer solar cells (PSCs) provide special opportunities for low-cost, printable, light-weight, flexible, and portable energy sources. For the past few years, a great advance to improve the efficiency of polymer solar cells has been achieved owing to development of new semiconducting polymers, understanding of organic semiconductor physics and advancement in the device optimization including interface engineering. As a result, the power conversion efficiency (PCE) has continuously increased to its current value over 8%. Nevertheless, further development of PSCs is still needed for commercialization, which requires the PCE higher than 10%. To enhance the PCE, many approaches has been proposed: (i) synthesis of low bandgap conjugated copolymers to harvest the solar spectrum more effectively, (ii) synthesis of semi-conducting polymers with deep HOMO levels to enhance V0 c, (iii) synthesis of planar conjugated polymers to afford high hole mobility, (iv) synthesis of new fullerene derivatives as acceptor material, and others.