Polymer with a 3D conductive network: a thickness-insensitive electron transport layer for inverted polymer solar cells

Abstract

A low-cost non-conjugated polymer, PEIE–DIO with a 3D conductive network, was developed by a simple quaterisation reaction between polyethyleneimine ethoxylate (PEIE) and 1,8-diiodooctane (DIO). The inverted PTB7-Th:PC₇₁BM PSCs with PEIE–DIO as an ETL achieve a PCE of 10.06%, and can keep a high PCE of 8.88% with 50 nm thick PEIE–DIO films, which are compatible with roll-to-roll techniques, making the fabrication of large-area devices at low cost possible.