A combined photoluminescence (PL) -detected magnetic-resonance (PLDMR) and thermally stimulated current (TSC) study of defects in wide-band-gap para-phenylene-type semiconductors is described. As TSC probes the density of mobile charge carriers after detrapping and PLDMR reveals the influence of trapped charges on the PL, their combination yields the concentration of traps, their energetic position, and their contribution to PL quenching. The reported trap densities, which are 2 x 10(16) for the polymer and 1 x 10(14) cm(-3), for the oligomer, are the lowest reported for para-phenylene-type materials. (C) 2000 American Institute of Physics. [S0003-6951(00)03615-9].