Exciton dissociation in organic light emitting diodes at the donor-acceptor interface

Experimental in situ photoluminescence and transient photovoltage results show that the interface formed by N,N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl) benzidine (NPB) and tris(8-hydroxyquinoline) aluminum (Alq(3)) acts as an exciton dissociation site. Because of this dissociation effect, excitons formed in NPB at or within a diffusion length of the interface tend to dissociate before they radiatively decay to generate blue light. This suggests that the action of the hole-blocking layer used in indium tin oxide\NPB\hole-blocking layer{Alq(3){aluminium to promote blue light emission from the NPB is more exciton dissociation inhibition than hole blocking.