Inverted Type Polymer Solar Cells with Self-Assembled Monolayer Treated ZnO

Abstract

The work function and surface property of ZnO can be simply tuned by the self-assembled monolayer (SAM) molecules derived from benzoic acid such as 4-methoxybenzoic acid (MBA), 4-tert-butylbenzoic acid (BBA), and 4-fluorobenzoic acid (FBA), which have different dipole orientation and magnitude. MBA, BBA, and FBA treated ZnO layers were used as an electron injection/transporting layer for inverted type polymer solar cells (PSCs) with a structure of ITO/SAM treated ZnO/active layer (P3HT:PC61BM)/MoO3/Ag. The power conversion efficiency (PCE) of PSCs based on MBA and BBA treated ZnO reaches 3.34 and 2.94%, respectively, while the PCE of the device based on untreated ZnO is 2.47%. In contrary, the PCE of the device with FBA treated ZnO is 1.81%. The open circuit voltage (Voc) of the device with MBA, BBA, and FBA treated ZnO is 0.63 and 0.62 V, respectively, while the Voc of PSC with untreated ZnO is 0.60 V. Contrarily, the Voc of the device with FBA treated ZnO is 0.53 V. The PCE and Voc of PSCs based on MBA ...