BLUE-PHOTON MODIFICATION OF NONSTANDARD DIODE BARRIER IN CUINSE2 SOLAR-CELLS

The current-voltage curves of many ZnO/CdS/CuInSe2 solar cells display significant distortion when only red light illumination is employed. This distortion generally disappears or partially disappears for a per iod of time following illumination with blue light. Similarly, the dar k diode curve shortly after illumination containing blue light is shif ted significantly from the equilibrium dark curve. This effect is more common than generally realized and indicates a mechanism that is pote ntially detrimental to photovoltaic efficiency. A model is presented t hat is based on a low free-electron concentration and a high concentra tion of deep levels in the CdS window layer. This model is consistent with observed variations in current-voltage, capacitance, and laser sc an data with illumination wavelength and history. (C) 1998 Elsevier Sc ience B.V. All rights reserved.