Polydopamine/ZnO nanocomposites as a new electron transport layer for PTB7: PC70BM solar cells

The excellent adhesion property of polydopamine (PDA) provides a new way to fixing nanoparticles . This study investigated the effects of PDA/ZnO nanocomposite as an electron transport layer (ETL) material on the performance of polythieno[3,4-b]-thiophene/benzodithiophene:[6,6]-phenyl-C70-butyric acid methyl ester bulk heterojunction solar cell . On one hand, the strong adhesive property of PDA to ZnO nanoparticles is beneficial to the formation of a uniform ZnO thin film , which is favorable for electron transfer. On the other hand, an energy level mismatch exists between PDA and ZnO, which hinders electron transfer from ZnO to ITO . Upon optimization, filling factor and photoelectric conversion efficiency are improved by 23.2% and 13.8%, respectively, when the single ZnO layer is replaced by PDA/ZnO nanocomposite as the ETL. Open circuit voltage resulted in 9.8% enhancement from 0.61   V to 0.67   V. However, the short circuit current density is reduced.