TECHNOLOGY FOCUS - POLYMERS - Preferred Component: The heterocyclic group (H1) is thiophene. The heterocyclic group (H2) is selenophene. The monomer (M1) is chosen from thiophene optionally substituted in 3-position and/or 4-position. The monomer (M2) is chosen from selenophene optionally substituted in 3-position and/or 4-position. The fully conjugated homopolymer (A) is of formula (I). The fully conjugated homopolymer (B) is of formula (II). The fully conjugated homopolymer (A) is poly(3-hexylthiophene). The fully conjugated homopolymer (B) is poly(3-hexylselenophene). The molar ratio of 3-hexylthiophene and 3-hexylselenophene is more than 1:200 and less than 200:1, preferably 1:1.R=H, NO2, NH2, COOH, CHO, F, Cl, Br, I, BH2, OH, SH, SeH, OR1, SR2, SeR3, COR4, functional group, or 1-100C hydrocarbyl optionally substituted hydrocarbyl and heteroatomic substituents;R1-R4=1-100C hydrocarbyl;andm,n=1-10000.Preferred Copolymer: The phase-separable block copolymer is phase-separated. The copolymer nanocrystal composite is crystalline. The phase-separable block copolymer is arranged in nanofibers. Several nanocrystals are substantially associated with a phase of phase-separable block copolymer. Nanocrystals are arranged in a substantially periodic linear fashion. Nanocrystals comprise spherical nanocrystals, cadmium-selenium nanocrystals, and an allotrope of carbon. The nanocrystals comprise compound chosen from cadmium selenide, cadmium telluride, cadmium sulfide, lead sulfide, lead selenide, copper indium sulfide, copper indium selenide, cadmium sulfide, cadmium phosphide, C60, phenyl-C61-butyric acid methyl ester, C70, phenyl-C71-butyric acid methyl ester, C84, carbon nanotube and graphene. The mass ratio of phase-separable block copolymer with respect to nanocrystals is 1:1. The phase-separable block copolymer is in electrical communication with nanocrystals. The nanocrystals have a conduction band of less than lowest unoccupied molecular orbital level of phase-separable block copolymer and a valence band less than highest occupied molecular orbital level of phase-separable block copolymer. The set of properties comprises morphological properties and optical properties.