Near-infrared Organic Photodetectors Research Articles

Copper Thiocyanate as an Anode Interfacial Layer for Efficient Near-Infrared Organic Photodetector

Interfacial modification between the electrode and the overlying organic layer has significant effects on the charge injection and collection and thus the device performance of organic photodetectors. Here, we used copper(I) thiocyanate (CuSCN) as the anode interfacial layer for organic photodetector, which was inserted between the anode and an organic light-sensitive layer. The CuSCN layer processed with ethyl sulfide solution presented similar optical properties to the extensively used anode interlayer of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), while the relatively shallow conduction band of CuSCN resulted in a much higher electron-injection barrier from the anode and shunt resistance than those of PEDOT:PSS. Moreover, the CuSCN-based device also exhibited an increased depletion width for the PEDOT:PSS-based device, as indicated by the Mott-Schottky analysis. These features lead to the dramatically reduced dark current density of 2.7 × 10-10 A cm-2 and an impressively high specific detectivity of 4.4 × 1013 cm Hz1/2 W-1 under -0.1 V bias and a working wavelength of 870 nm. These findings demonstrated the great potential of using CuSCN as an anode interfacial layer for developing high-performance near-infrared organic photodetectors.

Organic photodiodes for near-infrared light detection

High-sensitivity near-infrared organic photodetectors (NIR OPDs) have bright application prospects in the fields of optical communication, surveillance, chemical/biological detection and so on. In this review, we summarize recent works on NIR organic photodiodes and detail four main strategies: binary bulk heterojunctions (BHJs) with fullerene derivatives, binary BHJs with non-fullerene acceptors, ternary BHJs and a special kind of OPDs—visible blind NIR selective OPDs. Finally, based on the current development and challenges, we put forward the perspectives in this field.

Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors via morphology and dark current management

A side-chain engineered conjugated polymer provides outstanding NIR detectivity exceeding 2.0 × 1012Jones, due to enhanced photo-responsivity and suppressed dark current.

Correction: Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors via morphology and dark current management

Correction for ‘Side-chain engineering of conjugated polymers toward highly efficient near-infrared organic photo-detectors via morphology and dark current management’ by Yeongkwon Kang et al., J. Mater. Chem. C, 2020, 8, 7765–7771, DOI: 10.1039/D0TC00082E.

Correction to “Side-Chain Engineering of Nonfullerene Acceptors for Near-Infrared Organic Photodetectors and Photovoltaics”

Correction to “Side-Chain Engineering of Nonfullerene Acceptors for Near-Infrared Organic Photodetectors and Photovoltaics”

Exploration of Near-Infrared Organic Photodetectors

Near-infrared organic photodetectors (NIR OPDs) own some unique properties such as tailorable optoelectronic properties, ease of processing, compatibility with flexible substrates, and operation at...

Side-Chain Engineering of Nonfullerene Acceptors for Near-Infrared Organic Photodetectors and Photovoltaics

Narrow bandgap n-type molecular semiconductors are relevant as key materials components for the fabrication near-infrared organic solar cells (OSCs) and organic photodetectors (OPDs). We thus desig...

Inverted near-infrared organic photodetector with oriented lead (II) phthalocyanine molecules via substrate heating

We developed a lead (II) phthalocyanine (PbPc)-based inverted organic photodetector (OPD) detecting near-infrared (NIR) wavelength near 940 nm. Such inverted OPDs can be combined with n-channel silicon-based integrated circuits. Operation near 940 nm is crucial in terms of daylight applications because the intensity of sunlight is low near that wavelength. A spectral response to 1000 nm was achieved by depositing PbPc on a heated C60 layer to form a triclinic rather than a monoclinic phase. This exhibited a much higher responsivity (35.8 mA/W at 960 nm) compared to a device fabricated without substrate heating (8.4 mA/W). The external quantum efficiency also increased from 0.9 to 4.4%.

Electronic Level Alignment at an Indium Tin Oxide/PbI2 Interface and Its Applications for Organic Electronic Devices.

The electronic level alignment at the indium tin oxide (ITO)/PbI2 interface is investigated by an ultraviolet photoelectron spectroscopy. An n-type conductivity property is found for PbI2 as well as a downward shift energy level at the ITO/PbI2 interface. These indicate that PbI2 can be used as an anode buffer layer for organic electronic devices. The power conversion efficiency of the organic solar cell based on tetraphenyldibenzoperiflanthene/C70 planar heterojunction is dramatically increased from 1.05 to 3.82%. Meanwhile, the thermally activated delayed fluorescence organic light-emitting diode based on 4,4',4″-tri( N-carbazolyl)triphenylamine-((1,3,5-triazine-2,4,6-triyl)tris(benzene-3,1-diyl))tris(diphenylphosphine oxide) shows a significantly reduced turn-on voltage and enhanced power efficiency from 6.26 to 18.60 lm/W. The improved performance is attributed to the high hole injection/extraction efficiency at the ITO/PbI2 interface. Besides, the near-infrared (NIR) absorption of lead phthalocyanine (PbPc)-based NIR organic photodetector (NIR-OPD) is dramatically increased, indicating that the PbI2 layer can also be used as a template layer for the growth of the triclinic phase of PbPc. As a result, the optimized device shows an external quantum efficiency of 26.7% and a detectivity of 9.96 × 1011 jones at 900 nm, which are among the highest ones reported for organic NIR-OPDs.

Near-infrared organic photodetectors based on bay-annulated indigo showing broadband absorption and high detectivities up to 1.1 μm

Organic photodetectors made from a BAI-based near-infrared copolymer reach high detectivities of 1012 Jones and low dark currents of 10−7 A cm−2.

A trap-assisted ultrasensitive near-infrared organic photomultiple photodetector based on Y-type titanylphthalocyanine nanoparticles

An ultrasensitive near-infrared organic photodetector with an EQE of 354 200% and a photoresponsivity of 2227 A W−1 has been fabricated by dip-coating.

Double-side responsive polymer near-infrared photodetectors with transfer-printed electrode

Transfer-printed conducting polymer (tp-CP) is employed as the top electrode for near-infrared organic photodetectors. The double-side responsive photodetector exhibits a detectivity of 1013 Jones.

A highly sensitive near-infrared organic photodetector based on oxotitanium phthalocyanine nanocrystals and light-induced enhancement of electron tunnelling

A new single-layered organic photodetector was prepared, which exhibited a high photomultiplication gain of 356 at 830 nm.

Small-bandgap semiconducting polymers with high near-infrared photoresponse.

Lowering the optical bandgap of conjugated polymers while maintaining a high efficiency for photoinduced charge transfer to suitable electron acceptors such as fullerene has remained a formidable challenge in the area of organic photovoltaics. Here we present the synthesis and application of a series of ultra-small-bandgap donor-acceptor polymers composed of diketopyrrolopyrrole as acceptor and pyrrole-based groups as strong donors. The HOMO energy levels of the polymers can be progressively increased by increasing the donor strength while the LUMO level remains similar, resulting in optical bandgaps between 1.34 and 1.13 eV. Solar cells based on these polymers blended with fullerene derivatives show a high photoresponse in the near-infrared (NIR) and good photovoltaic characteristics, with power conversion efficiencies of 2.9-5.3%. The photoresponse reaches up to 50% external quantum efficiency at 1000 nm and extends to 1200 nm. With the use of a retro-reflective foil to optimize light absorption, high photocurrents up to 23.0 mA cm(-2) are achieved under standard solar illumination conditions. These ultra-small-bandgap polymers are excellent candidates for use in multi-junction applications and NIR organic photodetectors.