TECHNOLOGY FOCUS - ELECTRONICS - The semiconductor material comprises a p-type semiconductor material and an n-type semiconductor material.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - The p-type semiconductor material comprises a metal oxide containing an oxide selected from copper oxides, strontium copper oxides, and strontium titanium oxides. The p-type semiconductor material comprises a p-doped metal oxide. The p-doped metal oxide comprises p-doped zinc oxides or p-doped titanium oxides. The n-type semiconductor material comprises a metal oxide containing an oxide selected from titanium oxides, zinc oxides, tungsten oxides and/or molybdenum oxides. The n-type semiconductor material comprises a material selected from inorganic nanoparticles, discotic liquid crystals, carbon nanorods and/or inorganic nanorods. The hole blocking layer comprises a material selected from lithium fluoride (LiF) and/or metal oxides.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - The n-type semiconductor material comprises a material selected from fullerenes and/or oxadiazoles. The fullerene comprises (6,6)-phenyl-C61 butyric acid methyl ester (PCMB).    TECHNOLOGY FOCUS - POLYMERS - The p-type semiconductor material comprises a polymer selected from polythiophenes, polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, polycyclopentadithiophenes, polysilacyclopentadithiophenes, polycyclopentadithiazoles, polythiazolothiazoles, polythiazoles, polybenzothiadiazoles, poly(thiophene oxide)s, poly(cyclopentadithiophene oxide)s, polythiadiazoloquinoxalines, polybenzoisothiazoles, polybenzothiazoles, polythienothiophenes, poly(thienothiophene oxide)s, polydithienothiophenes, poly(dithienothiophene oxide)s, polytetrahydroisoindoles, and their copolymers (preferably poly(3,4-ethylene dioxythiophene)). The n-type semiconductor material comprises a material selected from polymers containing cyano (CN) groups, and/or polymers containing carbon tetra fluoride (CF3) groups. The p-type semiconductor material comprises poly(3-hexylthiophene) or poly(cyclopentadithiophene-co-benzothiadiazole). The hole carrier layer comprises a polymer selected from polythiophenes, polyanilines, polyvinylcarbazoles, polyphenylenes, polyphenylvinylenes, polysilanes, polythienylenevinylenes, polyisothianaphthanenes, and their copolymers.