III. New Molecular Design & Synthesis of D-π-A Copolymers
for Highly Efficient Polymer Solar Cells
Bulk heterojunction polymer solar cells (PSCs), which are based on solution-processable conjugated polymer donor and fullerene derivative acceptor materials, have attracted much attention in recent years, due to their advantages of easy fabrication, simple device structure, low cost, light weight, and capability to be fabricated into flexible devices. However, the power conversion efficiency still needs to be improved for the demand of commercialization. Therefore, present studies of the PSCs are mainly focused on increasing the efficiency of the devices, and the key point to increase the efficiency is the design and synthesis of high-efficiency conjugated polymer donor and fullerene derivative acceptor photovoltaic materials. For high-efficiency conjugated polymer donors, key requirements are a narrower energy bandgap (Eg) and broad absorption, relatively lower-lying HOMO (the highest occupied molecular orbital) level, and higher hole mobility. We focus on the rational design of conjugated polymers by influencing of each component on the physical and photovoltaic properties of polymers. In doing so, we have struggled to establish useful rules for the rational design of conjugated polymers with predictable properties.
