Improved organic optocouplers based on a deep blue fluorescent OLED and an optimized bilayer heterojunction photosensor

A deep blue fluorescent organic light emitting diode (OLED) and a structurally optimized organic photodiode (OPD) based on fullerene (C60)/N,N′-diphenyl-N,N′-bis(1-naphthyl)-1,1′-biphenyl-4,4′-diamine (NPB) bilayer heterojunction are coupled into an organic optocoupler (OOC). The demonstrations of overall design strategies show that the selection of OLED wavelength and the elimination of redundant thickness in OPD play important roles in improving the performance of OOC. With these efforts, the current transfer ratio of the OOC is significantly raised from previous 0.17% to 0.58%. The cut-off and following frequencies are 400 kHz and 1.25 MHz. Quantitative estimations indicate the external quantum efficiencies of OLED and OPD are about 4.3% and 32%, respectively.