NOVELTY - Photoconductivity, charge transport, solar energy conversion efficiency, or photovoltaic efficiency of organic semiconductor film is increased by adding low molecular weight alkyl-containing molecules to a solution of organic semiconductors, and forming the organic semiconductor film from the solution. The low molecular weight alkyl-containing molecules comprise 1-20C alkanes substituted with aldehyde, dioxo, hydroxy, alkoxy, thiol, or thioalkyl.    USE - Increasing the photoconductivity, charge transport, solar energy conversion efficiency, or photovoltaic efficiency of organic semiconductor film used in electronic device such as solar cell, photovoltaic cell, photodetector, photodiode, or phototransistor (claimed).    ADVANTAGE - The method provides improved performance characteristics of the films, including photoconductivity, charge transport, solar conversion efficiency, and/or photovoltaic efficiency, by modifying an internal structure or morphology of organic semiconductor films.    DETAILED DESCRIPTION - Increasing the photoconductivity, charge transport, solar energy conversion efficiency, or photovoltaic efficiency of organic semiconductor film, involves adding an amount of low molecular weight alkyl-containing molecules to solution of organic semiconductors, and forming the organic semiconductor film from the solution. The low molecular weight alkyl-containing molecules comprise 1-20C alkanes substituted with aldehyde, dioxo, hydroxy, alkoxy, thiol, thioalkyl, carboxylic acid, ester, amine, amide, ether, thioether, halide, fluoride, chloride, bromide, iodide, nitrile, epoxide, aromatic, or arylalkyl. It is provided that if a thiol or hydroxy substituent is present, a chosen additional substituent must also be present. It is also provided that di-halo substituted compounds are excluded from the low molecular weight alkyl-containing molecules.    DESCRIPTION OF DRAWING(S) - The drawing is a graph showing transmittance through films for films on glass substrates.