Abstract
Solar energy conversion efficiency of n-CuInSe2/p-CuISe3 heterojunction formed in situ and contacted by I−-I2-Cu+-HI electrolyte has been increased to 12% by modifying the growth conditions of the p-CuISe3 phase. These include the use of prepolished n-CuInSe2 (110) surfaces, higher concentrations of HI and Cu+, and an air anneal at 200 °C. X-ray fluorescence analysis in conjunction with scanning electron micrographs of the new interphase indicates structural and compositional alterations and possibly further transformation of CuISe3 to CuIn2Se3I. Temperature dependence of the cell performance indicates solid state effects and relative independence of electrochemical kinetics.