Photo-Response of Low Voltage Flexible TIPS-Pentacene Organic Field-Effect Transistors
TL;DR: In this paper, photo-response of solution processed flexible TIPS-pentacene organic field effect transistors is evaluated under illumination with visible light of red, green, and blue colors having minimum wavelengths of 620, 520, and 460 nm.
Abstract: Photo-response of solution processed flexible TIPS-pentacene organic field-effect transistors is evaluated under illumination with visible light of red, green, and blue colors having minimum wavelengths of 620, 520, and 460 nm. For −10 V operation, pristine photo-OFETs exhibited average field-effect mobility of 0.11 cm $^{2}\text{V}^{-1}\text{s}^{-1}$ , near zero threshold voltage, and current ON–OFF ratio of ~105. These photo-OFETs exhibited prevalent photovoltaic characteristics with shift in the threshold voltage upon illumination, which was found to increase with rising intensity, illumination time, and gate bias during illumination. For low-voltage operation at −5 V, maximum current modulation of $4\times 10^{4}$ and 102, and photo-responsivity of 17 mA/W and 35 mA/W, respectively, were achieved for blue (intensity of 1.7 mW/cm2) and green (intensity of 0.4 mW/cm2) light illuminations. However, these photo-OFETs did not show significant response to red light. A fast dynamic response to periodic pulses of illumination was also observed. For a gate bias of +10 V and illumination time of 500 s, maximum current modulation of 105 was achieved for blue light illumination.
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TL;DR: In this paper , the authors used gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor to achieve a low leakage current and low-voltage operation.
Abstract: Organic field-effect transistors (OFETs) have opened up new possibilities as key elements for skinlike intelligent systems, due to the capability of possessing multiple functionalities. Here, multifunctional OFET devices based on gelatin, a natural biopolymer gate dielectric, and TIPS-pentacene as an organic semiconductor are extensively explored. Gelatin is combined with a thin high-k HfO2 dielectric layer deposited by atomic layer deposition (ALD) to achieve a low leakage current and low-voltage operation. The natural biopolymer offers a better semiconductor:dielectric interface, leading to better charge conduction in the devices, along with an enhancement of sensing capabilities giving additional functionality. These fabricated flexible OFET devices exhibit excellent electrical characteristics with a high field-effect mobility reaching over 2 cm2/(V s) (extracted with Ci at 1 kHz), a low subthreshold swing (SS) of ∼200 mV/dec, and a high current on–off (Ion/Ioff) ratio at a low operating voltage of −5 V with excellent electrical and mechanical stability. Moreover, circuit and multiparameter sensing capabilities for visible and UV light, as well as for humidity and breath rate, have been successfully demonstrated for these devices. Our results indicate that these multifunctional OFET devices can open up a plethora of opportunities for practical applications such as real-time health and environmental monitoring.
10 citations
TL;DR: In this article, the effect of ultra-violet (UV) irradiation on the electrical characteristics of solution processed flexible TIPS-pentacene organic field effect transistors (OFETs) has been investigated.
9 citations
TL;DR: In this article, a combination of a thin layer of copper (II) phthalocyanine (CuPc) and TIPS-pentacene crystal was used to enhance the photo-sensing spectrum of photo-sensitive organic field effect transistors (photo-OFETs).
9 citations
TL;DR: In this paper, the crucial role of molecular weight of the polymer dielectric in regulating the electrical performance and photo-response of TIPS-pentacene OFETs has been explored using poly(vinyl alcohol) (PVA) as the polymer layer.
4 citations
References
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TL;DR: In this paper, the integration of a 4μm thick sensor layer onto a flexible amorphous silicon thin-film transistor backplane gave an image sensor array with 35% external quantum efficiency and noise equivalent power of 30pW∕cm2 at reverse bias voltage of −4V.
Abstract: Thick organic bulk heterojunction photodiodes with low dark current 1V∕μm is sufficient to achieve >75% charge collection in films of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene-vinylene] and [6,6]-phenyl-C61-butyric acid methyl ester blends up to 4μm thick, and the rate of photocurrent decay is reduced at saturation fields. The integration of a 4μm thick sensor layer onto a flexible amorphous silicon thin-film transistor backplane gave an image sensor array with 35% external quantum efficiency and noise equivalent power of 30pW∕cm2 at reverse bias voltage of −4V.
283 citations
"Photo-Response of Low Voltage Flexi..." refers background in this paper
...However, some of the donor-acceptor systems show high performance and are extensively explored which include P3HT/ PCBM [23]–[25], PPV derivatives/PCBM [26], [27], F8BT/PDI [28], PTT/PCBM [29], PCPDTBT/ PCBM [30], PEDOT:PSS/PCDTBT:PCBM [31], EHTPPDMT/PCBM [32], and PEDOT:PSS/PCBM:BCP [33]....
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TL;DR: In this article, a review of the fabrication, challenges, and sensor performance of organic transistor-based detection devices with an outlook toward developing sensors capable of operating in biologically relevant media is presented.
234 citations
"Photo-Response of Low Voltage Flexi..." refers background in this paper
...including chemical sensing [10]–[12], bio-sensing [13], gas sensing [14], [15], and pressure sensing [16]....
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TL;DR: It is shown that the compatibility of organic semiconductors with high-k gate dielectrics allows boosting the current drive of transistors in functional circuits to EPC compatible clock rates.
232 citations
"Photo-Response of Low Voltage Flexi..." refers background in this paper
...OFETs have already been successfully integrated in several applications like flexible displays [6], [7], radio frequency identification (RFID) tags [8], and wearable devices [9]....
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TL;DR: In this paper, the photocurrent action spectra of conjugated polymers poly[2-methoxy, 5 ethyl (2-ensuremath{'} hexyloxy) paraphenylenevinylene] (MEH-PPV) and poly(phenylene-vinylene) (PPV), were measured in sandwich cells between indium tin oxide (ITO) and aluminum electrodes.
Abstract: We have measured the photocurrent action spectra of the conjugated polymers poly[2-methoxy, 5 ethyl (2\ensuremath{'} hexyloxy) paraphenylenevinylene] (MEH-PPV) and poly(phenylenevinylene) (PPV) in sandwich cells between indium tin oxide (ITO) and aluminum electrodes. Under forward bias and illumination through ITO, the photocurrent spectrum is broad and has a maximum at high energy, where the absorption coefficient is greatest (the symbatic response). Under reverse bias and illumination through ITO, the photocurrent spectrum consists of a very narrow peak (the full width at half maximum is 0.1 eV), located in the low-energy tail of the absorption profile (the antibatic response). Several established models attempt to explain this behavior and to relate the photocurrent action spectrum to the absorption coefficient, considering penetration depth of the light and diffusion of excitons or directly photogenerated charges. At a qualitative level many of these seem to provide an adequate description. In this paper, we undertake a quantitative examination of these models and we find that none of them can reproduce the very narrow antibatic response that we observe in both MEH-PPV and PPV. Upon exposure to air, we observe an enhancement of the photocurrent by a much greater factor than the dark current, from which we conclude that charge generation is mediated by exciton dissociation. As the temperature decreases we observe a progressive redshift of the absorption edge, although the photocurrent onset undergoes a much smaller redshift. We therefore conclude that the narrow antibatic peak is due to a specific enhancement of dissociation upon excitation at low energy. We propose that the particularly sharp onset of photocurrent at low energy may be due to enhanced intermolecular charge separation within crystallite grains between those neighboring conjugated segments that are more extended and more planar.
195 citations
"Photo-Response of Low Voltage Flexi..." refers background in this paper
...1(e), suggesting an antibatic behavior [49], [50]....
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...Excitons which are generated in the vicinity of interface (distance shorter than diffusion length), can reach to interface, and contribute towards photo-induced effects [49]–[51]....
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TL;DR: In this paper, the photoelectronic characteristics of single-crystalline nanowire organic phototransistors (NW-OPTs) were studied using a high-performance n-channel organic semiconductor, N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI), as the photoactive layer.
Abstract: The photoelectronic characteristics of single-crystalline nanowire organic phototransistors (NW-OPTs) are studied using a high-performance n-channel organic semiconductor, N,N′-bis(2-phenylethyl)-perylene-3,4:9,10-tetracarboxylic diimide (BPE-PTCDI), as the photoactive layer. The optoelectronic performances of the NW-OPTs are analyzed by way of their current–voltage (I–V) characteristics on irradiation at different wavelengths, and comparison with corresponding thin-film organic phototransistors (OPTs). Significant enhancement in the charge-carrier mobility of NW-OPTs is observed upon light irradiation as compared with when performed in the dark. A mobility enhancement is observed when the incident optical power density increases and the wavelength of the light source matches the light-absorption range of the photoactive material. The photoswitching ratio is strongly dependent upon the incident optical power density, whereas the photoresponsivity is more dependent on matching the light-source wavelength with the maximum absorption range of the photoactive material. BPE-PTCDI NW-OPTs exhibit much higher external quantum efficiency (EQE) values (≈7900 times larger) than thin-film OPTs, with a maximum EQE of 263 000%. This is attributed to the intrinsically defect-free single-crystalline nature of the BPE-PTCDI NWs. In addition, an approach is devised to analyze the charge-transport behaviors using charge accumulation/release rates from deep traps under on/off switching of external light sources.
183 citations
"Photo-Response of Low Voltage Flexi..." refers background in this paper
...Quantitatively, these rates can be calculated using following expression [48],...
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...In addition, external quantum efficiency (EQE) was calculated which is the ratio of photo-generated carriers increasing the drain current to the number of incident photons in the channel area [48]....
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