Multi-Polarization Sensitive Organic Photodetectors

Detection of polarization states of the polarized light is critical for a plethora of applications in areas such as image sensors, environmental monitoring, light communications, security monitoring, health monitoring, bio/medical analysis, military reconnaissance, artificial vision, remote sensors, digital cameras, mobile phones, and polarimetric information displays. Different polarization states of the incident light are determined using multiple photodetectors incorporating polarizers having different polarization sensitivities. For example, a conventional polarimetric imaging system uses an array of discrete photodetectors having polarizers/compensators with a rotated polarization position relative to their nearest neighbors, combining multiple discrete photodetectors with an array of micro polarizers/retarders, or employing polarization beam splitters. However, the polarimetric imaging system with a photodetector array has limitation in spatial resolution. The use of a photodetector array for polarization detection has technical limitations, as it is difficulty to integrate the optical components, such as the polarization beam splitters and micro polarizers/retarders, with electronics for compact system at low cost.

This project proposes to develop a novel multi-polarization sensitive organic photodetector (OPD) using a back-to-back stacked anisotropic P-polarization/Spolarization sensitivity double heterojunction structure. For example, the front P3HT:Y6-based anisotropic polarization sensitive junction, prepared using floating film transfer method, is aligned for responding to the P-polarized light, whereas the rear P3HT:Y6-based anisotropic polarization sensitive junction is aligned for responding to the S-polarized light. The use of a back-to-back stacked anisotropic P -polarization/Spolarization sensitive double heterojunction in the OPD allows a multi-polarization sensitive detection that is controlled by the polarity of a bias voltage applied between the two contacts in the device. The polarization sensitive photodetection technology will be critical for development of advanced computer vision in robotics, automated manufacturing, health monitoring, bio/medical analysis, and other applications across various industries.