Enhanced spectral coverage in tandem organic solar cells

In order to realize enhanced spectral coverage in organic photovoltaic devices, the authors have stacked a zinc phthalocyanine:C-60 based cell on the top of a poly-3-hexyl-thiophene:[6,6]-phenyl C-61-butyric acid methyl ester layer using a 1 nm thick Au intermediate recombination layer. Such tandem devices comprising active materials with complementary absorption spectra exhibit a short circuit current (I-sc) of 4.8 mA cm(-2), an open circuit voltage (V-oc) of 1020 mV, and a fill factor of 0.45. Measurements of the photocurrent versus wavelength of the incident light show that photons are converted into charge carriers from 400 to more than 800 nm. Further optimization of the respective layer thicknesses may lead to high efficiency devices. (c) 2006 American Institute of Physics.