High-Sensitivity Visible–Near Infrared Organic Photodetectors Based on Non-Fullerene Acceptors

Abstract

Highly sensitive solution-processed organic photodetectors (OPDs) with a broadband response ranging from visible to near infrared (NIR) and excellent overall device performance are demonstrated. The OPDs were fabricated from a blend consisting of a wide-band gap polymer donor and a newly developed fused octacylic small-molecule electron acceptor with an acceptor–donor–acceptor structure, which shows relatively high and balanced hole/electron mobility and allows for a thicker photo-active layer (∼300 nm). In conjunction with the use of an optimized inverted device structure, the dark current density of the OPDs was suppressed to an ultralow level of (8.3 ± 5.5) × 10–10A cm–2 at a bias of −1 V and the capability to direct weak light intensity is down to 0.24 pW cm–2; both are among the lowest reported values for OPDs. Owing to the low shot noise enabled by the inverted structure and the low thermal noise due to the high shunt resistance of the device, the obtained OPDs show a spectrally flat photoresponse in the range of 350–950 nm (UV–vis–NIR) and a maximal specific detectivity (D*) of (2.1 ± 0.1) × 1013 Jones at 800–900 nm, which are among the best results of NIR OPDs reported to date and represents a highly sensitive photodetector for weak optical signal detection. Besides, the OPDs show a wide bandwidth of 30 kHz, a fast temporal response time around 12 us ∼14 us, and a large linear dynamic range of 106 dB.

Double‐Side Crystallization Tuning to Achieve over 1 µm Thick and Well‐Aligned Block‐Like Narrow‐Bandgap Perovskites for High‐Efficiency Near‐Infrared Photodetectors

“…The self‐powered optimized PDs present the fast response speed with the rise time ( t rise ) of 58.3 ns and the fall time ( t fall ) of 0.86 us, suggesting it can offer fast detection and imaging applications. [ 61 ] This result indicates the efficient photocurrent extraction within DSCT‐produced perovskite NIR PDs contributed by the high‐quality Sn–Pb thick perovskite films.…”

Low Band Gap Conjugated Semiconducting Polymers

“…Y. Cao and coworkers reported a detectivity of 2 × 10 13 cm Hz 1/2 W −1 for a detector made of a polymer from the PTB‐family and NFA. [ 57 ]…”

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

“…Relative to visible absorbing molecules, NIR organic molecules pose additional challenges in device performance, that is, the efficiency loss due to the reduction of energy level offsets for exciton dissociation and the high dark current owing to the decline of barrier heights for charge blocking under reverse bias. [ 7,9 ] Nonetheless, recent efforts have led to significant boosts in the performance of NIR OPDs using either polymers [ 10–13 ] or small molecule materials. [ 14–19 ] For instance, Xiong et al.…”

“…Relative to visible absorbing molecules, NIR organic molecules pose additional challenges in device performance, that is, the efficiency loss due to the reduction of energy level offsets for exciton dissociation and the high dark current owing to the decline of barrier heights for charge blocking under reverse bias. [7,9] Nonetheless, recent efforts have led to significant boosts in the performance of NIR OPDs using either polymers [10][11][12][13] or small molecule materials. [14][15][16][17][18][19] For instance, Xiong et al investigated solutionprocessed polymer NIR OPDs with PMDPP3T:PC 61 BM bulk heterojunction (BHJ), exhibiting a low dark current density (J d ) of 3.0 nA cm −2 at −0.2 V and a high external quantum efficiency (EQE) of 48% at 850 nm (a responsivity of 0.37 A W −1 ) for broad sensing applications.…”