cuprous oxide, with a band gap of 2.0 ev, is an attractive material for solar cells because of low cost and great availability. the current conversion efficiency is 1, but theoretical estimates are 13. for various schottky barriers, e.g., al/cu sub 2 o, it is proposed that the v/sub oc/ is limited by chemical conversion of the junctions to cu/cu sub 2 o junctions, and the model is supported by auger and esca results. it is proposed to avoid the reaction by use of an oxide interlayer as in al/al sub 2 o sub 3 /cu sub 2 o, which also gives an mis structure, but only minimal success has yet been achieved with the methods tried. sb sub 2 o sub 3 and sio/sub x/ layers were explored. another approach could be to use oxide heterojunctions on cu sub 2 o. several were explored and zno/cu sub 2 o was best. in and cd are effective dopants for cu sub 2 o. with samples annealed at 500 exp 0 c, diffusion lengths of approximately 4 mu m were measured by an spv method. the spectral sensitivity of cu/cu sub 2 o cells has a threshold at 630 nm and a maximum at 500 nm. (era citation 04:000416)