Perovskite/Organic Bulk‐Heterojunction Integrated Ultrasensitive Broadband Photodetectors with High Near‐Infrared External Quantum Efficiency over 70%

Abstract

Ultraviolet-visible-near infrared (UV-Vis-NIR) broadband detection is important for image sensing, communication, and environmental monitoring, yet remains as a challenge in achieving high external quantum efficiency (EQE) in the broad spectrum range. Herein, sensitive broadband integrated photodetectors (PDs) with high EQE levels are reported. The organic bulk-heterojunction (OBHJ) layer, based on a NIR sensitive organic acceptor, is employed to extend the response spectrum of the perovskite PDs. A key strategy of introducing dual electron transport materials respectively for Vis and NIR regions into the active layer of integrated PDs is applied. Further combined with the proper energy level alignment and reasonable distribution of PC BM in the active layer, the extraction and transport of photo induced charges in between perovskite and OBHJ is promoted efficiently. The integrated PD with the optimized structure exhibits an EQE mostly beyond 70% in the Vis-NIR region, which is the highest value among the ever reported solution-processable broadband PDs. The highest responsivity is 0.444 and 0.518 A W in the Vis and NIR region, respectively. The specific detectivity is beyond 10 Jones in the range from 340 to 940 nm, enabling the device to detect weak signals in the UV to NIR broad region.

Ultrafast and broadband photodetectors based on a perovskite/organic bulk heterojunction for large-dynamic-range imaging

“…Organic-inorganic hybrid perovskites (OIHPs) are emerging materials that have been progressively enabling new thin-film optoelectronics, including solar cells [21][22][23][24][25][26][27] , light-emitting diodes 28,29 and photodetectors 14,16,[30][31][32][33][34][35][36] . The extensive application of hybrid perovskites can be attributable to their excellent optical and electrical properties, including a direct bandgap, large absorption coefficient, high carrier mobility, and low trap density [37][38][39][40] .…”

“…However, the detection range of MAPbI 3 (either polycrystalline films or thin single crystals) is limited to the wavelength region below 820 nm and does not cover the near-infrared (NIR) range, which severely limits its application, especially in biomedical imaging. To overcome this problem, an advantageous strategy has been demonstrated: combining OIHP and an organic bulk heterojunction (BHJ) consisting of donor-acceptor materials with light absorption in the NIR region 16,35,36,42 . Shen et al reported a composite photodetector based on MAPbI 3 and PDPPTDTPT/PCBM, which exhibited a wider detection wavelength extending to 950 nm with a 5 ns ultrafast response time 16 .…”

Recent Progress on Broadband Organic Photodetectors and their Applications

“…Reproduced with permission. [92] Copyright 2018, Wiley-VCH. g) Absorption spectra of different films by spin coating, the inset is the chemical structures of F8IC and PTB7-Th and h) EQE curves of the IPD, pure perovskite and pure BHJ devices at zero bias.…”

A self-powered, flexible ultra-thin Si/ZnO nanowire photodetector as full-spectrum optical sensor and pyroelectric nanogenerator

“…The detectivity D* is one of the key parameters of a PD, which usually describes the ability to detect weak signals. The photoresponsivity is calculated by Equation 2 [3]: (2) where R, S, q, and I dark represent responsivity, illuminated area, electronic charge, and dark current, respectively. The calculated detectivity D* of our device is as high as 10 13 Jones.…”

“…Full-spectrum photodetectors (PDs) that can detect light from ultraviolet to near-infrared have attracted widespread attention in recent years for a variety of applications in industry and technology, such as optical sensing/communication, environmental monitoring, biomedicine, and the "internet of things" [1][2][3][4]. Especially full-spectrum PDs applied in flexible wearable elec-tronic devices have been extensively researched [5].…”