Role of tungsten oxide in inverted polymer solar cells

Tungsten oxide (WO3) was inserted as an anode interfacial layer between the photoactive layer and top electrode in inverted polymer solar cells (PSCs) with nanocrystalline titanium dioxide as an electron selective layer. The device with WO3 exhibited a remarkable improvement in power conversion efficiency compared with that without WO3, which indicated that WO3 efficiently prevented the recombination of charge carriers at the organic/top electrode interface. The dependence of the device performances on WO3 film thickness and different top metal electrodes was investigated. Transparent inverted PSCs with thermally evaporable Ag/WO3 as a transparent anode were also investigated when introducing a WO3 buffer layer.