Enhanced efficiency of polymer photovoltaic cells via the incorporation of a water-soluble naphthalene diimide derivative as a cathode interlayer

Abstract

In this contribution, a novel cathode interlayer material (NDIO) based on naphthalene diimide was successfully prepared by a facile two-step reaction from commercially available compounds. NDIO exhibited excellent water solubility, high transparency in the visible light region, and well-matched molecular energy levels. By incorporating this novel water processed cathode interlayer, a high power conversion efficiency of 9.51% was recorded in PBDT-TS1/PC₇₁BM-based polymer photovoltaic cells (PPCs), and the value is nearly 2-fold the device efficiency of PPCs without the cathode interlayer. More importantly, the insertion of the NDIO interlayer promotes the device efficiency of polymer/polymer photovoltaic cells based on PBDTTT-EFT/N2200 from 3.23% up to 5.77%. The successful applications in both polymer/PCBM and polymer/polymer blend-based inverted PPCs make NDIO a promising cathode interlayer for realizing aqueous processed polymer photovoltaic cells with high performance.