Options for fabrication and design of CuInSe2 based solar cells

Three options for the fabrication and design of CuInSe₂-based solar cells are presented. Single-phase CulnSe ₂ films have been deposited in a closed-loop selenization reaction system using Se to convert Cu/In layers. The system operates as a thermosiphon to circulate Ar gas containing elemental Se across the substrates, which eliminates the hazards associated with H₂Se gas. An approach to increasing V_OC without loss in J_SC using a thin higher bandgap Cu(InGa)Se₂ layer deposited on the CuInSe₂ is demonstrated. Devices with V_OC~0.5 V and collection to 1.0 eV have been fabricated. CuInSe₂/CdS cells in a superstrate configuration have been fabricated by depositing CuInSe₂, on a glass/ITO/CdS substrate. Cells with efficiencies near 6% have been made with a J_SC comparable to high-efficiency cells, but the present devices have a V_OC<0.35 V