Copper thiocyanate: An attractive hole transport/extraction layer for use in organic photovoltaic cells

Abstract

We report the advantageous properties of the inorganic molecular semiconductor copper(I) thiocyanate (CuSCN) for use as a hole collection/transport layer (HTL) in organic photovoltaic (OPV) cells. CuSCN possesses desirable HTL energy levels [i.e., valence band at -5.35eV, 0.35eV deeper than poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS)], which produces a 17% increase in power conversion efficiency (PCE) relative to PEDOT:PSS-based devices. In addition, a two-fold increase in shunt resistance for the solar cells measured in dark conditions is achieved. Ultimately, CuSCN enables polymer:fullerene based OPV cells to achieve PCE>8%. CuSCN continues to offer promise as a chemically stable and straightforward replacement for the commonly used PEDOT:PSS.