Inkjet‐Printed Microlenses Integrated onto Organic Photodiodes for Highly Accurate Proximity Sensing

Abstract The current needs for optical detectors in industrial and consumer electronics require sensors with thin form‐factors, high performance and a facile fabrication and integration. In this work, the integration of inkjet printed microlenses onto solution‐processed organic photodiodes is demonstrated to enable high‐accuracy proximity sensing via the focused induced photoresponse (FIP) effect. By precisely controlling the ink deposition and substrate properties, it is able to tune the microlens focal length from 150 to 775 μm. This allows to the appropriate microlens design to be chosen to take advantage of the FIP effect. By comparing the photocurrent ration of a device with and without microlenses, absolute proximity measurements in the range of 100 μm to 4 mm are achieved. Champion devices yield an accuracy of down to ±50 μm within three standard deviations (3σ). These results highlight the potential of the microlens‐OPD integration for highly accurate and close‐distance proximity applications in a variety of fields.