The theory of space-charge-limited currents (SCLC) is briefly reviewed and the spectroscopic character of the method is discussed. Shapes of current-voltage characteristics of thin films strongly depend on temperature, presence of charge carrier traps and their distribution in energy, spatial inhomogeneity of the sample and electrode configuration. The presence of traps influences generation-recombination noise which can be used as additional information for the determination of density-of-states function. The use of the technique is illustrated with experimental results obtained on thin films of phthalocyanines. (c) 2008 Published by Elsevier B.V.