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Highly Responsive and Thermally Reliable Near-Infrared Organic Photodiodes Utilizing Naphthalocyanine Molecules Tuned with Axial Ligands

Advanced Optical Materials

Achieving high-performance near infrared (NIR) photodiodes is in great demand for potential applications like biometrics, security, artificial visions, biomedical imaging, etc. Herein, silicon naphthalocyanine (SiNc) small molecule-based NIR photodiodes with narrowband absorption are presented. The optimized photodiode by varying the axial ligand in the SiNc molecules exhibits a high external quantum efficiency of 76.6% at 795 nm with narrow full width at half maximum of 80 nm, a very low dark current of 1.07 nA cm-2 at a reverse bias of -3 V, and the resultant detectivity of 5.66 × 1012 Jones. Further increase of the detectivity up to 1013 Jones is obtained by modulating the applied bias to -1 V, which to the best of our knowledge is among the highest values of organic NIR detectors reported to date. The SiNc-based photodiodes are further characterized by temporal response, linear dynamic range, etc., and shown to be stable in high humidity for over a month and in a remarkably wide temperature range (-55°C to 125°C). It is highly likely that the developed SiNc-based photodiodes can be applicable to a wide variety of NIR sensor platforms.

Adv. Optical Mater. 2020, 2001682