NOVELTY - Organic light-emitting diode, organic solar cell or switching element comprises at least one substituted carbazole derivative (A).    USE - The organic light-emitting diode, organic solar cell or switching element is useful in stationary visual display units including visual display units of computers, televisions, visual display units in printers, kitchen appliances and advertising panels, illuminations, information panels, mobile visual display units (including visual display units in cell phones, laptops, digital cameras, moving picture experts group audio layer 3 (mp3) players, vehicles and destination displays on buses and trains), illumination units, keyboards, garments, furniture and wallpapers comprising at least one organic light-emitting diode, organic field effect transistors and an organic thin film transistor.    ADVANTAGE - The organic light-emitting diode, organic solar cell or switching element has high efficiency, improved lifetime and improved color purity.    DETAILED DESCRIPTION - Organic light-emitting diode, organic solar cell or switching element comprises at least one substituted carbazole derivative (A) of formula (I), (II) or (III).    X = NR4, O, S or PR4;    Y1 = NR5, O, S or PR5, (where at least one of X or Y1 is NR4 or NR5); either    R1, R3 = 1-20C alkyl, 6-30C aryl, heteroaryl having 5-30 ring atoms (all optionally substituted) or substituent with donor or acceptor action (including 1-20C alkoxy, 6-30C aryloxy, 1-20C alkylthio, 6-30C arylthio, SiR6R7R8, halo, halogenated 1-20C alkyl, -CO(R6), -C=O(SR6), -C=O(OR6), -OC=O(R6), -SC=O(R6), -NR6R7, OH, pseudohalo, -C=O(NR6), -NR6C=O(R7), -P(O)(OR6)2, -OP(O)(OR6)2, -PR6R7, -P(O)(R6)2, -OS(O)2OR6, -S(O)R6, -S(O)2OR6), -S(O)2R6, -S(O)2NR6R7, NO2, -OB(OR6)2, -C=NR6R7, boranyl, stannyl, hydrazinyl, hydrazonyl, oxime, nitrosyl, diazo, vinyl, sulfoximines, alanes, germanes, boroximes or borazinyl); or    CR1R1, CR3R3 = ring having 3-12 atoms (optionally substituted, saturated or mono or polyunsaturated, optionally having at least one heteroatom including N, O or P, and optionally fused to further 3-12 membered rings), where at least one of R1 or R3, when it is arranged in the para position to X or Y1, is bonded via a heteroatom including Si, Ge, O, S or P or via sp3-hybridized carbon atom; either    R2 = 1-20C alkyl, 6-30C aryl, heteroaryl having 5-30 ring atoms (all optionally substituted) or substituent with donor or acceptor action (including 1-20C alkoxy, 6-30C aryloxy, 1-20C alkylthio, 6-30C arylthio, SiR6R7R8, halo, halogenated 1-20C alkyl, -CO(R6), -C=O(SR6), -C=O(OR6), -OC=O(R6), -SC=O(R6), -NR6R7, OH, pseudohalo, -C=O(NR6), -NR6C=O(R7), -P(O)(OR6)2, -OP(O)(OR6)2), -PR6R7, -P(O)(R6)2, -OS(O)2OR6, -S(O)R6, -S(O)2OR6, -S(O)2R6, -S(O)2NR6R7, NO2, boronic esters (-OB(OR6)2, imino -C=NR6R7, boranyl, stannyl, hydrazinyl, hydrazonyl, oxime, nitrosoyl, diazo, vinyl, sulfoximines, alanes, germanes, boroximes or borazinyl; or    CR2R2 = 3-12C ring (optionally saturated or mono- or polyunsaturated, optionally mono- or polysubstituted ,and/or optionally fused to further 3-12 membered rings);    R4, R5 = 6-30C aryl or 1-20C alkyl (both optionally substituted); either    R6-R8 = 1-20C alkyl or 6-30C aryl, heteroaryl having 5-30 ring atoms (all optionally substituted), -O-Si(1-20C alkyl)3, -O-Si(6-30C aryl)3, 1-20C alkoxy, 6-30C aryloxy or halogenated 1-20C alkyl; or    CR6R7, CR6R8 or CR7R8 = ring having 3-12 atoms (optionally mono- or polyunsaturated, optionally having heteroatoms including N, O or P, optionally mono- or polysubstituted and/or optionally fused to further 3-12 membered rings);    l, n = 0-4, where at least l or n is 1-4; and    m = 0-2.    INDEPENDENT CLAIMS are also included for:    (1) substituted carbazole derivative (A) of formula (I), (II) or (III);    (2) a light-emitting layer comprising at least one substituted carbazole derivative (A) and at least one emitter material; and    (3) use of substituted carbazole derivatives (A) as matrix material, hole/exciton blocker material and/or electron/exciton blocker material and/or hole injection material and/or electron injection material and/or hole conductor material and/or electron conductor material in an organic light-emitting diode, an organic solar cell or in a switching element.