Ultrahigh photosensitive organic phototransistors by photoelectric dual control
23 Apr 2019-Journal of Materials Chemistry C (The Royal Society of Chemistry)-Vol. 7, Iss: 16, pp 4725-4732
TL;DR: In this paper, a novel OPT working mode by photoelectric dual control is reported, where after each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by device converting to accumulation mode when the light is on.
Abstract: Organic phototransistors (OPTs) simultaneously introduce photo-induced holes and electrons into the structure of organic field-effect transistors (OFETs). The memory effect of the minority carrier is the origin of the large dark current and slow response during the light on/off switching, which is detrimental to the OPT performance and cycling stability. In this research, we report a novel OPT working mode by photoelectric dual control. After each light switch, the dark current is erased by the gate voltage in depletion mode which remains unchanged during light off; the photocurrent increases by device converting to accumulation mode when the light is on. In this way, high performance OPTs have been obtained in an FBT-Th4(1,4) : PC61BM (5 : 1) composite film with the structure of Si/SiO2/OTS/FBT-Th4(1,4) : PC61BM/Au electrodes, which shows a broad spectral response (maximum values at zero gate bias: R 1.2 × 105 A W−1, gain 3.7 × 105 and D* 3.18 × 1016 Jones) from 410 to 740 nm (calculated from the transfer curve). The best performance with photoelectric dual control under 0.0031 mW cm−2@405 nm is achieved with an on/off current ratio of 1.0 × 106, response 1.6 × 104 A W−1, gain 5.0 × 104, spectral detectivity 2.3 × 1017 Jones and response time sub-40 ms, which makes the phototransistor a very promising component for light sensing applications.
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TL;DR: In this Review, recent advances in device architectures and operation mechanisms of phototransistor, photoconductor, and photodiode based OPDs are reviewed with a focus on the strategies aiming at performance improvement.
Abstract: Organic photodetectors (OPDs) have attracted continuous attention due to their outstanding advantages, such as tunability of detecting wavelength, low-cost manufacturing, compatibility with lightweight and flexible devices, as well as ease of processing. Enormous efforts on performance improvement and application of OPDs have been devoted in the past decades. In this Review, recent advances in device architectures and operation mechanisms of phototransistor, photoconductor, and photodiode based OPDs are reviewed with a focus on the strategies aiming at performance improvement. The application of OPDs in spectrally selective detection, wearable devices, and integrated optoelectronics are also discussed. Furthermore, some future prospects on the research challenges and new opportunities of OPDs are covered.
170 citations
07 Jan 2021
TL;DR: In this article, flexible organic ion-gated transistors based on the high mobility donor-acceptor conjugated copolymer poly[4-(4,4-dihexadecyl 4H-cyclopenta[1,2-b:5, 4-b′]-dithiophen-2-yl)-alt [1, 2,5]thiadiazolo[3,4c]pyridine] as the ionic liquid [1-ethyl-3 methylimidazolium bis(trifluorometh
Abstract: Ion-gated transistors are attracting significant attention due to their low operating voltage (<1 V) and modulation of charge carrier density by ion-gating media. Here we report flexible organic ion-gated transistors based on the high mobility donor–acceptor conjugated copolymer poly[4-(4,4-dihexadecyl 4H-cyclopenta[1,2-b:5,4-b′]-dithiophen-2-yl)-alt[1,2,5]thiadiazolo[3,4c]pyridine](PCDTPT) and the ionic liquid [1-ethyl-3 methylimidazolium bis(trifluoromethylsulfonyl)imide] as the ion-gating medium. Electrical characteristics of devices made on both [rigid (SiO2/Si) and flexible (polyimide (PI))] substrates showed very similar values of hole mobility (∼1 cm2 V−1 s−1) and ON–OFF ratio (∼105). Flexible ion-gated transistors showed good mechanical stability at different bending curvature radii and under repetitive bending cycles. The mobility of flexible ion-gated transistors remained almost unchanged upon bending. After 1000 bending cycles the mobility decreased by 20% of its initial value. Flexible photodetectors based on PCDTPT ion-gated transistors showed photosensitivity and photoresponsivity values of 0.4 and 93 AW−1.
8 citations
TL;DR: In this article, an n/p/electret tri-layer configuration is used to assist reversible charge injection and depletion of insulator electrets, and illumination is employed to assist hole and electron insertion and depletion.
Abstract: A semiconductor/electret layered configuration is attractive for organic field-effect transistors, and the reversible generation of hole or electron charged electrets within the device requires effective charge transport in the semiconductor. Here, in a transistor with an n/p/electret tri-layer configuration, illumination is used to assist reversible charge (hole and electron) injection and depletion of insulator electrets.
8 citations
TL;DR: In this article , a diffusion interface layer is formed between the channel layer and BHJ layer after treating the film transfer method (FTM)-based NIR phototransistors with solvent vapor annealing (SVA).
Abstract: The narrow bandgap of near-infrared (NIR) polymers is a major barrier to improving the performance of NIR phototransistors. The existing technique for overcoming this barrier is to construct a bilayer device (channel layer/bulk heterojunction (BHJ) layer). However, acceptor phases of the BHJ dissolve into the channel layer and are randomly distributed by the spin-coating method, resulting in turn-on voltages (Vo) and off-state dark currents remaining at a high level. In this work, a diffusion interface layer is formed between the channel layer and BHJ layer after treating the film transfer method (FTM)-based NIR phototransistors with solvent vapor annealing (SVA). The newly formed diffusion interface layer makes it possible to control the acceptor phase distribution. The performance of the FTM-based device improves after SVA. Vo decreases from 26 V to zero, and the dark currents decrease by one order of magnitude. The photosensitivity (Iph/Idark) increases from 22 to 1.7 × 107.
7 citations
References
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2,020 citations
TL;DR: This work demonstrates polymer photodetectors with broad spectral response fabricated by using a small-band-gap semiconducting polymer blended with a fullerene derivative that can exceed the response of an inorganic semiconductor detector at liquid helium temperature.
Abstract: Sensing from the ultraviolet-visible to the infrared is critical for a variety of industrial and scientific applications. Today, gallium nitride-, silicon-, and indium gallium arsenide--based detectors are used for different sub-bands within the ultraviolet to near-infrared wavelength range. We demonstrate polymer photodetectors with broad spectral response (300 to 1450 nanometers) fabricated by using a small-band-gap semiconducting polymer blended with a fullerene derivative. Operating at room temperature, the polymer photodetectors exhibit detectivities greater than 10(12) cm Hz(1/2)/W and a linear dynamic range over 100 decibels. The self-assembled nanomorphology and device architecture result in high photodetectivity over this wide spectral range and reduce the dark current (and noise) to values well below dark currents obtained in narrow-band photodetectors made with inorganic semiconductors.
1,580 citations
TL;DR: This review suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto -electronic switch and memory.
Abstract: While organic electronics is mostly dominated by light-emitting diodes, photovoltaic cells and transistors, optoelectronics properties peculiar to organic semiconductors make them interesting candidates for the development of innovative and disruptive applications also in the field of light signal detection. In fact, organic-based photoactive media combine effective light absorption in the region of the spectrum from ultraviolet to near-infrared with good photogeneration yield and low-temperature processability over large areas and on virtually every substrate, which might enable innovative optoelectronic systems to be targeted for instance in the field of imaging, optical communications or biomedical sensing. In this review, after a brief resume of photogeneration basics and of devices operation mechanisms, we offer a broad overview of recent progress in the field, focusing on photodiodes and phototransistors. As to the former device category, very interesting values for figures of merit such as photoconversion efficiency, speed and minimum detectable signal level have been attained, and even though the simultaneous optimization of all these relevant parameters is demonstrated in a limited number of papers, real applications are within reach for this technology, as it is testified by the increasing number of realizations going beyond the single-device level and tackling more complex optoelectronic systems. As to phototransistors, a more recent subject of study in the framework of organic electronics, despite a broad distribution in the reported performances, best photoresponsivities outperform amorphous silicon-based devices. This suggests that organic phototransistors have a large potential to be used in a variety of optoelectronic peculiar applications, such as a photo-sensor, opto-isolator, image sensor, optically controlled phase shifter, and opto-electronic switch and memory.
1,081 citations
TL;DR: A way of integrating photonics with silicon nanoelectronics is described, using polycrystalline silicon on glass islands alongside transistors on bulk silicon complementary metal–oxide–semiconductor chips to address the demand for high-bandwidth optical interconnects in data centres and high-performance computing.
Abstract: Electronic and photonic technologies have transformed our lives-from computing and mobile devices, to information technology and the internet. Our future demands in these fields require innovation in each technology separately, but also depend on our ability to harness their complementary physics through integrated solutions1,2. This goal is hindered by the fact that most silicon nanotechnologies-which enable our processors, computer memory, communications chips and image sensors-rely on bulk silicon substrates, a cost-effective solution with an abundant supply chain, but with substantial limitations for the integration of photonic functions. Here we introduce photonics into bulk silicon complementary metal-oxide-semiconductor (CMOS) chips using a layer of polycrystalline silicon deposited on silicon oxide (glass) islands fabricated alongside transistors. We use this single deposited layer to realize optical waveguides and resonators, high-speed optical modulators and sensitive avalanche photodetectors. We integrated this photonic platform with a 65-nanometre-transistor bulk CMOS process technology inside a 300-millimetre-diameter-wafer microelectronics foundry. We then implemented integrated high-speed optical transceivers in this platform that operate at ten gigabits per second, composed of millions of transistors, and arrayed on a single optical bus for wavelength division multiplexing, to address the demand for high-bandwidth optical interconnects in data centres and high-performance computing3,4. By decoupling the formation of photonic devices from that of transistors, this integration approach can achieve many of the goals of multi-chip solutions 5 , but with the performance, complexity and scalability of 'systems on a chip'1,6-8. As transistors smaller than ten nanometres across become commercially available 9 , and as new nanotechnologies emerge10,11, this approach could provide a way to integrate photonics with state-of-the-art nanoelectronics.
630 citations
TL;DR: Inverted solar cells with active layer thicknesses ranging from 100 to 440 nm display PCEs exceeding 6.5%, with the highest efficiency of 7.64% achieved with a 230 nm thick active layer.
Abstract: Absorption spectra of polymer FBT-Th4 (1,4) (M n = 46.4 Kg/mol, E g = 1.62 eV, and HOMO = -5.36 eV) indicate strong interchain aggregation ability. High hole mobilities up to 1.92 cm(2) (V s)(-1) are demonstrated in OFETs fabricated under mild conditions. Inverted solar cells with active layer thicknesses ranging from 100 to 440 nm display PCEs exceeding 6.5%, with the highest efficiency of 7.64% achieved with a 230 nm thick active layer.
366 citations