TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The anode is formed with the material selected from indium tin oxide, indium zinc oxide, carbon nanotube, nickel, platinum, gold, silver, iridium, aluminum or their oxide. The quantum dot optical device also comprises cadmium sulphide, zinc selenide or zinc sulphide. The hole-transport layer comprises titanium dioxide, zinc oxide, silicon dioxide, tin dioxide, tungsten oxide, zirconium dioxide, hafnium dioxide, tantalum pentoxide, barium titanium oxide, barium zirconium oxide, aluminum oxide, yttrium oxide or zirconium orthosilicate. The quantum dot comprises zinc oxide, silicon dioxide, tin dioxide, zirconium dioxide, tungsten oxide, hafnium dioxide, tantalum pentoxide, barium titanium oxide, barium zirconium oxide, aluminum oxide, yttrium oxide or zirconium orthosilicate. The electron-injecting electrode is made of calcium, barium, calcium or aluminum, aluminum or magnesium, aluminum or magnesium. The electron-transport layer comprises titanium dioxide, zinc oxide, silicon dioxide, tin dioxide, tungsten oxide, zirconium dioxide, hafnium dioxide, tantalum pentoxide, barium titanium oxide, barium zirconium oxide, aluminum oxide, yttrium oxide or zirconium orthosilicate. The quantum dot light-emitting layer comprises II-VI group compound semiconductor nanocrystal, III-V group compound semiconductor nanocrystal, IV-VI group compound semiconductor nanocrystal, IV group compound semiconductor nanocrystal or their mixture. The II-VI group compound semiconductor nanocrystal comprises homochemical compound including elements selected from cadmium-selenium-sulphur, cadmium-selenium-tellurium, cadmium-sulphur-tellurium, zinc-selenium-sulphur, zinc-selenium-tellurium, zinc-sulphur-tellurium, cadmium-zinc-sulphur, cadmium-zinc-selenium, cadmium-zinc-tellurium, cadmium-zinc-selenium-sulphur, cadmium-zinc-selenium-tellurium, cadmium-zinc-sulphur-tellurium, cadmium-mercury-selenium-sulphur, cadmium-mercury-selenium-telluriuim, cadmium-mercury-sulphur-tellurium, mercury-zinc-selenium-sulphur, mercury-zinc-selenium-tellurium, mercury-zinc-sulphur-tellurium, cadmium-selenium, cadmium-tellurium, zinc-sulphur, zinc-selenium or zinc-tellurium. The III-V group compound semiconductor nanocrystal comprises homochemical compound including elements selected from gallium-nitrogen-phosphorus, gallium-nitrogen-arsenic, gallium-nitrogen-antimony, gallium-phosphorus-arsenic, gallium-phosphorus-antimony, indium-nitrogen-phosphorus, indium-nitrogen-arsenic, indium-nitrogen-antimony, indium-phosphorus-arsenic, indium-phosphorus-antimony, gallium-aluminum-nitrogen-phosphorus, gallium-aluminum-nitrogen-arsenic, gallium-aluminum-nitrogen-antimony, gallium-aluminum-phosphorus-arsenic, gallium-aluminum-phosphorus-antimony, gallium-indium-nitrogen-phosphorus, gallium-indium-nitrogen-arsenic, gallium-indium-nitrogen-antimony, gallium-indium-phosphorus-arsenic, gallium-indium-phosphorus-antimony, indium-aluminum-nitrogen-phosphorus, indium-aluminum-nitrogen-arsenic, indium-aluminum-nitrogen-antimony, indium-aluminum-phosphorus-arsenic, indium-aluminum-phosphorus-antimonyl, gallium-nitrogen, gallium-phosphorus, gallium-arsenic, gallium-antimony, indium-phosphorus, indium-arsenic or indium-antimony. The IV-VI group compound semiconductor nanocrystal comprises homochemical compound including elements selected from lead-selenium-sulphur, lead-selenium-tellurium, lead-sulphur-tellurium, tin-lead-sulphur, tin-lead-selenium, tin-lead-tellurium, tin-lead-sulphur-selenium, tin-lead-selenium, tin-lead-sulphur-tellurium, lead-sulphur, lead-selenium or lead-tellurium. The IV group compound semiconductor nanocrystal comprises homochemical compound including elements selected from silicon-carbon, silicon-germanium, silicon or germanium.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components:The hole-transport layer are also selected from poly(3,4- ethylenedioxythiophene)/polystyrene parasulfonate, poly-N-vinylcarbazole, polyphenylenevinylene, polyparaphenylene, polymethaacrylate, poly (9,9-octylfluorene), poly(spirofluorene), N,N'-diphenyl-N,N'-bis 3-methyl-phenyl-1,1'-biphenyl-4,4'-diamine, poly(9,9-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine), copper phthalocyanine, polyvinylcarbazole or their derivative.