Nanostructured Cathode Buffer Layers for Inverted Polymer Solar Cells

Abstract

Polymer solar cells (PSCs) based on polymer donor-fullerene derivative acceptor bulk heterojunction (BHJ) active layer have attracted considerable attention as a promising alternative to conventional silicon-based solar cells due to their cost effectiveness, compatible with flexible substrate and solution-based roll-to-roll processing technique. Inverted PSC seems to be the best candidate that meets the requirements for both high efficiency and good stability. To achieve high power conversion efficiency (PCE) in inverted PSCs, the selection of an appropriate nanostructured cathode buffer layer (CBL) so as to optimize the electron collection and transport is particularly important. Nanostructured zinc oxide (ZnO) CBLs have been the most extensively studied CBLs for inverted PSCs in view of its relatively high electron mobility, high optical transparency, ease of being synthesized with low cost solution methods at low temperature, versatile morphologies, and being environmentally stable. This chapter focuses on the design, fabrication and characterization of the nanostructured CBLs constructed with pristine ZnO, doped-ZnO, and ZnO-based composites as well as the surface modified ZnO-based CBLs for the improvement of PCE and long-term device stability of inverted PSCs.