A ZnO:POMs composite electron transport layer for efficient PTB7:PC71BM polymer solar cells

Suitable modification to the ZnO cathode interface of polymer solar cells can effectively enhance the efficiency, stability, and electron extraction capability of the device. With the use of vacant Keggin type PW polyoxometalates (POMs), polymer solar cells with ZnO:POM composite electron transport layer (ETL) were prepared. Compared with the single ZnO ETL, the addition of POMs mainly improved the interface contact and reduced the charge transfer barrier, which was conducive to exciton dissociation and charge collection. When the doping concentration of POMs was 0.1 mg/mL, the power conversion efficiency of the device with the structure of ITO/ZnO-PW11-0.1/PTB7: PC71BM/MoO3/Al could reach 8.66%, which was 18.5% higher than that of the control device (7.31%).