Enhancement of photoelectric conversion efficiency in copper phthalocyanine solar cell by surface plasmon excitation

In order to enhance the photoconversion efficiency, surface plasmon polaritons (SPP) in an organic solar cell consisting of Al, copper phthalocyanine (CuPc) and Ag thin films were excited by an attenuated total reflection (ATR) method. The dependence of the enhancement factor for the short-circuit current (Isc) on the wavelength of the incident light (Λin) was measured in detail in the visible region. It was found that the enhancement factor depends strongly on Λin and takes a maximum (a factor of 8) around Λin=550 nm. The good agreement between the calculated Λin dependence of light absorption in the CuPc layer and the observed Λin dependence of the enhancement factor suggests that the enhancement is caused by increased carrier generation in the CuPc layer due to increased light absorption upon SPP excitation.