High Efficient Inverted Polymer Solar Cells with Solution-Processed Electron Transport Layer

We demonstrate highly efficient solar cell polymer with an inverted structure (iPSCs) based on PTB7:PC
₇₀
BM and PTB7-Th:PC
₇₀
BM. The effects of solution-processed PFN, ZnO, and TiOx as an electron transporting layer (ETL) on the performance of iPSCs are investigated. Devices using ZnO as ETL exhibit the highest power conversion efficiency (PCE = 9.5
^%
). Additional impedance spectroscopy measurements demonstrate that charge carrier collection in iPSCs is limited by the series and shunt resistances driven by the hole transporting layer.