PHOTOLUMINESCENCE IN POLYCRYSTALLINE CUINSE2 SOLAR-CELLS

Photoluminescence (PL) data have been reported by several workers for both single-crystal and polycrystalline CuInSe//2, including actual solar cells. Comparison shows a substantial agreement among the PL transitions reported and a consistent defect energy level diagram. Correction is made for the electrostatic term in the PL transition energy which can be quite large for polycrystalline material and which can be used to estimate defect densities. Physical arguments are presented to identify the primary levels. The dominant donor proposed is the selenium vacancy, a double donor which would have ionization energies near 40 and 70 mev. The dominant acceptor proposed is copper on an indium site, also a double level with near-hydrogenic energies of 40 and 80 mev.