Organic Bifunctional Devices with Emission and Sensing Abilities

Organic bifunctional devices with emission and sensing abilities were reviewed and a prototype of a matrix was demonstrated. There are two types of device structure: a bi-function matrix array (Bi-Matrix) with a stacked layer of organic light-emitting diode (OLED) and organic photodiode (OPD) matrix arrays, and a multi-function diode (MFD) which has a structure similar to that of conventional OLED and has two functions of emission and photosensing. For the Bi-Matrix, independent operations of emission and photosensing were achieved; the maximum luminance of its OLED was 77,400 cd/m2 and the ratio of photoconductivity to dark conductivity was 1×104. A prototype 4×4 Bi-Matrix was also demonstrated. For the MFD, a special organic material, the pyrazoline derivative, was used. The highest luminance obtained was 9,270 cd/m2 under a forward bias condition. The highest photocurrent density was 71 µA/cm2 and the highest ratio of photo- to dark-conductivity was 1×104 under a reverse-bias condition. Details of the prototype 16×16 MFD matrix were also described.