Conjugated Polymer Photovoltaic Materials

The Institute of Organic Solids of the Chemistry Institute CAS recently achieved major advances in the research of new conjugated polymer photovoltaic materials for polymer solar energy cells.    The research team has designed and synthesized branch-chain conjugated polythiophene containing a conjugated branch chain (styrene or thiophene ethylene). Polythiophene derivatives with broad or strong absorption coefficient in the visible zone can be obtained by adjusting the length of the conjugated branch chain or the ratio of thiophene elements on the branch chain. Polythiophene containing a di-thiophene ethylene branch chain displays a 380-650 nm wide and strong absorption bar. Polymer solar energy cells prepared through the blending of this polymer with C60 derivative PCBM (weight ratio 1:1) has a maximum energy conversion rate of 3.18% in simulated sunlight, being 38% higher than that of poly(3-hexylthiophene) in popular use today.    Besides, the research team has also made achievements in conjugated polymer materials with high migration rate. It has designed and synthesized a cross-linking polythiophene derivative containing a conjugated bridging group. The cavity mobility rate of polymers containing 5% conjugated bridge is 2 orders of magnitude higher than polymers with no conjugated bridge. Their photovoltaic property is also greatly improved.