Increasing The Efficiency Of A Multilayer Bulk Heterojunction Solar Cell Using Water-Soluble Conjugated Polymer As An Electron Injection Layer

A bulk heterojunction solar cell (BHJ-SC) was fabricated from the conventional active polymer blend P3HT:PCBM by constructing a polymer multilayer structure with novel electron-transporting water-soluble conjugated polymers (WSCPs), poly[9,9'-bis[2-(2-(2-(6 ''-(N,N,N-trimethylammonium)ethoxy) ethoxy) ethoxy) ethyl] fluorine, and its copolymer with a phenyl on top of the polymer active layer. In the multilayer structure BHJ-SC, each WSCP coordinated by Na+ ions to the oxygen site on the side chain of the polymer acts as a good electron injection layer for the higher electron collection at the cathode metal. This causes up to 85% increase in the BHJ-SC's power conversion efficiency (PCE) compared to that of the BHJ-SC without WSCPs. This report will discuss the effect of the electron injection layer in the BHJ-SC in terms of the current/voltage characteristics, PCE, electron affinity, and charge mobility of water-soluble polymers.