Build-on Technology of Bidirectional Optical Communication System Using Bifunctional Organic Diodes

A bidirectional optical communication system using bi-functional organic diodes (BiORDs) has been investigated. The stacked structure used was a front transparent organic light emitting diode (TOLED) and a back organic photodiode (OPD). For a device structure of LiF (1 nm)/semitransparent AlNd (15 nm)/MoO3 (30 nm)/TPD (100 nm)/td-PTC (perylene derivative, 50 nm)/Al, a maximum luminance of 77,400 cd/m2 and a ratio of photo- to dark current of 1,100 were obtained. As a result, an excellent linearity range between the input TOLED current and the output OPD current was obtained at over three orders of magnitude. Cutoff frequencies of the TOLED and OPD were 1.4 MHz and 150 kHz, respectively. For an optical transmission experiment, random burst waveforms of return-to-zero and nonreturn-to-zero were applied to the BiORDs, and an operational frequency of 100 kbps was realized.