Single crystalline pentacene solar cells

Pentacene single crystals were grown from the vapor phase and doped with io dine. Schottky-type solar cells were prepared based on these p-type crystal s using rf-magnetron sputtered n-type ITO-window layers and Al or Mg back c ontacts, respectively. The improvement of the photovoltaic properties due t o iodine doping is related to (1) a higher conductivity resulting in a lowe r series resistance of the devices, (2) a shift of the absorption edge lead ing to a better match to the solar spectrum, and (3) an increased internal quantum efficiency. The devices were analyzed by measurements of the quantu m efficiency, current-voltage curves, and capacitance-voltage characteristi cs. The solar cells exhibit open circuit voltages up to 955 mV, short circu it current densities of 4.5 mA/cm(2), and filling factors in the range of 0 .45 resulting in a maximum conversion efficiency of 1.9% for a standard sol ar spectrum(AM1.5, 100 mW/cm(2)). (C) 2000 Elsevier Science S.A. All rights reserved.