TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Compound: The group II-VI semiconductor material is chosen from cadmium sulfide, cadmium telluride, cadmium selenide, zinc telluride, zinc selenide, zinc sulfide, magnesium telluride, cadmium selenium telluride, cadmium zinc telluride, cadmium manganese telluride, cadmium magnesium telluride and cadmium mercury telluride. The main tunnel junction comprises semiconductor layer containing zinc telluride, zinc sulfide, magnesium telluride, cadmium zinc telluride or cadmium magnesium telluride. The upper subcell comprises material chosen from cadmium tin oxide, tin oxide, zinc selenide, titanium oxide, magnesium telluride, zinc oxide, zinc sulfide, magnesium selenide, indium tin oxide, magnesium sulfide, silica and magnesium fluoride. The lower base and substrate are formed from group IV semiconductor chosen from silicon, germanium and their mixture. The lower emitter comprises a semiconductor layer containing silicon, germanium, cadmium telluride, cadmium selenide, zinc telluride, cadmium selenium telluride, cadmium zinc telluride, cadmium manganese telluride, cadmium magnesium telluride or cadmium mercury telluride. The upper base comprises a material chosen from cadmium telluride, cadmium selenide, cadmium selenium telluride, cadmium zinc telluride, cadmium magnesium telluride and cadmium mercury telluride. The primary emitter comprises a semiconductor layer containing cadmium sulfide, cadmium selenide, zinc telluride, zinc selenide, zinc sulfide, magnesium telluride, cadmium selenium telluride, cadmium zinc telluride, cadmium manganese telluride and cadmium magnesium telluride. The primary base comprises material chosen from cadmium selenium telluride, cadmium zinc telluride and cadmium magnesium telluride. The tunnel junction comprises a material chosen from zinc telluride, zinc sulfide, magnesium telluride, zinc sulfide, cadmium zinc telluride and cadmium magnesium telluride. The secondary emitter comprises a material chosen from cadmium sulfide, zinc telluride, zinc selenide, zinc sulfide, cadmium manganese telluride, cadmium zinc telluride and cadmium magnesium telluride. At least one layer of the primary tunnel junction comprises a material chosen from zinc telluride, zinc sulfide, magnesium telluride, zinc oxide, cadmium zinc telluride, cadmium manganese telluride and cadmium magnesium telluride. The secondary base comprises a semiconductor material chosen from cadmium sulfide, zinc telluride, zinc selenide, zinc sulfide, cadmium zinc telluride, cadmium manganese telluride and cadmium magnesium telluride. At least one layer of the secondary tunnel junction comprises a material chosen from zinc telluride, zinc sulfide, magnesium telluride, zinc oxide, cadmium zinc telluride and cadmium magnesium telluride.