controlled the energy levels of donor polymers by introducing cyano (CN) and alkoxy (OR) groups into the 4,4′-didodecyl-2,2′-bithiophene (BT) unit in a step-by-step fashion, thereby varying the inductive and resonance effects. The three monomer units (BT, BTC, and BTCox) were polymerized with benzo[1,2-b:4,5-b′]dithiophene (BDT) as a counter unit to afford three polymers (PBDT-BT, PBDT-BTC, and PBDT-BTCox).
精细调节供体聚合物的能级是实现聚合物太阳能电池(PSC)高功率转换效率的至关重要的一步。我们通过逐步地将
氰基(CN)和烷氧基(OR)基引入4,4'-二癸基-2,2'-联
噻吩(BT)单元来系统地控制供体聚合物的能级,从而改变感应效应和共振效应。将三个单体单元(BT,
BTC和
BTCox)与苯并[1,2-b:4,5- b']二
噻吩(BDT)作为对位单元,可提供三种聚合物(
PBDT-BT,
PBDT-
BTC和
PBDT-
BTCox)。引入CN基团后,最高占据的分子轨道能级和最低的未占据的分子轨道能级显着下降,并且当OR基团连接时,这些能级略有增加,这与三个聚合物器件的测量开路电压高度吻合。
PBDT-
BTCox中存在的强感应和共振效应将聚合物带隙缩小到1.74 eV,以提供5.06%的功率转换效率,这是三种聚合物中实现的最高值。