Incorporation of potassium at CuPc/C60 interface for photovoltaic application

This letter demonstrates the effect of potassium (K) doping at the donor–acceptor interface of CuPc/C60-based organic solar cells. Power conversion efficient (PCE) doubled when a little K was doped into the CuPc/C60 interface and the device was postannealed (75 °C, 10 min). Changes in binding energies, depletion capacitance, and mobilities of electrons and holes were investigated. The marked improvement of PCE arose mostly from the increase in short-circuit current, owing to the modified charge transfer process.