Semitransparent organic photovoltaic cells

We demonstrate semitransparent, small molecular weight organic solar cells employing a thin silver/indium tin oxide compound cathode with a maximum transmission of (60 +/- 6)% averaged over the visible spectral range and with a power conversion efficiency, eta(P)=(0.28 +/- 0.03)% under simulated, AM1.5G, 1. sun illumination. By increasing the Ag thickness, an average transmission of (26 +/- 3)% is achieved with eta(P)=(0.62 +/- 0.06)%, a value approximately half of that obtained for the same structure employing a conventional, reflective, and thick Ag cathode. A semitransparent tandem organic solar cell with eta(P)=(0.48 +/- 0.02)% and an average transmission of (44 +/- 4)% is also demonstrated. Semitransparent organic photovoltaic cells have potential uses as tinted and power-generating thin-film coatings on architectural surfaces, such as windows and walls. The use of a transparent top electrode also significantly simplifies the design of tandem cells, relaxing requirements for the placement of different absorbing materials at the maxima of optical fields introduced by reflective cathodes. (c) 2006 American Institute of Physics.