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1.
Novel 2D semiconductors play an increasingly important role in modern nanoelectronics and optoelectronics. Herein, a novel topology designer based on component fusion is introduced, featured by the submolecular component integration and properties inheritance. As expected, a new air-stable 2D semiconductor PdPSe with a tailored puckered structure is successfully designed and synthesized via this method. Notably, the monolayer of PdPSe is constructed by two sublayers via P P bonds, different from 2D typical transition metal materials with sandwich-structured monolayers. With the expected orthorhombic symmetry and intralayer puckering, PdPSe displays a strong Raman anisotropy. The field-effect transistors and photodetectors based on few-layer PdPSe demonstrate good electronic properties with high carrier mobility of ≈35 cm2 V−1 s−1 and a high on/off ratio of 106, as well as excellent optoelectronic performance, including high photoresponsivity, photogain, and detectivity with values up to 1.06 × 105 A W−1, 2.47 × 107%, and 4.84 × 1010 Jones, respectively. These results make PdPSe a promising air-stable 2D semiconductor for various electronic and optoelectronic applications. This work suggests that the component-fusion-based topology designer is a novel approach to tailor 2D materials with expected structures and interesting properties.  相似文献   

2.
《Organic Electronics》2008,9(3):285-290
The triazine compound 4,4′-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1′-biphenyl (BTB) was developed for use as an electron transport material in organic light emitting devices (OLEDs). The material demonstrates an electron mobility of ∼7.2 × 10−4 cm2 V−1 s−1 at a field of 8.00 × 105 V cm−1, which is 10-fold greater than that of the widely used material tris(8-hydroxyquinoline) aluminum (AlQ3). OLEDs with a BTB electron transport layer showed a ∼1.7–2.5 V lower driving voltage and a significantly increased efficiency, compared to those with AlQ3. These results suggest that BTB has a strong potential for use as an OLED electron transport layer material.  相似文献   

3.
Simultaneously integrating efficient optical gain and high charge carrier mobility in organic semiconductors for multifunctional optoelectronic applications is challenging. Here, a new thiophene/phenylene derivative, 5,5′‐bis(2,2‐diphenylvinyl)‐bithiophene (BDPV2T), containing an appropriate butterfly molecular configuration in a π‐conjugated structure, is designed to achieve both solid‐state emission and charge transport properties. The prepared BDPV2T crystals exhibit excellent light‐emitting characteristics with a photoluminescence quantum yield of 30%, low light‐amplification threshold of 8 kW cm?2, high optical net gain up to 70 cm?1, and high charge carrier mobility up to 1 cm2 V?1 s?1 in their J‐aggregate single crystals. These BDPV2T single crystal characteristics ensure their application potential for photodetectors, field‐effect transistors, and light‐emitting transistors. High optoelectronic performances are achieved with photoresponsivity of 2.0 × 103 A W?1 and light on/off ratio of 5.4 × 105 in photodetectors, and efficient ambipolar charge transport (µh: 0.14 cm2 V?1 s?1, µe: 0.02 cm2 V?1 s?1) and electroluminescence characteristics in light‐emitting transistors. The remarkably integrated optoelectronic properties of BDPV2T suggest it is a promising candidate for organic multifunctional and electrically pumped laser applications.  相似文献   

4.
CuCr0.93Mg0.07O2 thin films were successfully deposited by DC reactive magnetron sputtering at 1123 K from metallic targets. The influence of film thickness on the structural and optoelectronic properties of the films was investigated. X-ray diffraction (XRD) results revealed that all the films had a delafossite structure with no other phases. The optical and electrical properties were investigated by UV–VIS spectrophotometer and Hall measurement, respectively. It was found that the optoelectronic properties exhibited a thickness-dependent behavior. The optical band gap and the average transmittance of the films showed a monotonous decrease with respect to the increase in thickness. The average transmittance in the visible region decreased from 67% to 47% as the thickness increased from ~70 nm to ~280 nm. Simultaneously, the conductivity of the films fell from 1.40 S∙cm−1 to 0.27 S∙cm−1. According to Haacke's figure of merit (FOM), a film with a maximum FOM value of about 1.72×10−7 Ω−1 can be achieved when the thickness is about 70 nm (σ≈ 1.40 S·cm−1 and Tav. ≈67%).  相似文献   

5.
Optoelectronic performance of 2D transition metal dichalcogenides (TMDs)-based solar cells and self-powered photodetectors remain limited due to fabrication challenges, such as difficulty in doping TMDs to form p–n junctions. Herein, MoS2 diodes based on geometrically asymmetric contact areas are shown to achieve a high current rectification ratio of ≈105, facilitating efficient photovoltaic charge collection. Under solar illumination, the device demonstrates a high open-circuit voltage (Voc) of 430 mV and a short-circuit current density (Jsc) of −13.42 mA cm−2, resulting in a high photovoltaic power conversion efficiency (PCE) of 3.16%, the highest reported for a lateral 2D solar cell. The diodes also show a high photoresponsivity of 490.3 mA W−1, and a large photo detectivity of 4.05 × 1010 Jones, along with a fast response time of 0.8 ms under 450 nm wavelength at zero bias for self-powered photodetection applications. The device transferred on a flexible substrate shows a high photocurrent and PCE retentions of 94.4%, and 88.2% after 5000 bending cycles at a bending radius of 1.5 cm, respectively, demonstrating robustness for flexible optoelectronic applications. The simple fabrication process, superior photovoltaic properties, and high flexibility suggests that the geometrically asymmetric MoS2 device architecture is an excellent candidate for flexible photovoltaic and optoelectronic applications.  相似文献   

6.
Dense point defects can strengthen phonon scattering to reduce the lattice thermal conductivity and induce outstanding thermoelectric performance in GeTe-based materials. However, extra point defects inevitably enlarge carrier scattering and deteriorate carrier mobility. Herein, it is found that the interstitial Cu in GeTe can result in synergistic effects, which include: 1) strengthened phonon scattering, leading to ultralow lattice thermal conductivity of 0.48 W m−1 K−1 at 623 K; 2) weakened carrier scattering, contributing to high carrier mobility of 80 cm2 V−1 s−1 at 300 K; 3) optimized carrier concentration of 1.22 × 1020 cm−3. Correspondingly, a high figure-of-merit of ≈2.3 at 623 K can be obtained in the Ge0.93Ti0.01Bi0.06Te-0.01Cu, which corresponds to a maximum energy conversion efficiency of ≈10% at a temperature difference of 423 K. This study systematically investigates the doping behavior of the interstitial Cu in GeTe-based thermoelectric materials for the first time and demonstrates that the localized interstitial Cu is a new strategy to enhance the thermoelectric performance of GeTe-based thermoelectric materials.  相似文献   

7.
Semiconductors based on Bi element show large attenuation coefficients to X-ray photons and have been recognized as candidates for X-ray detectors. However, the application of stable Bi-based oxide materials to X-ray detectors has been rarely investigated. In this research, the X-ray response of a BiVO4 pellet has been studied. It has been found that the BiVO4 pellet has a large resistivity of 1.3 × 1012 Ω cm, negligible current drift of 6.18 × 10−8 nA cm−1 s−1 V−1 under electrical bias and mobility lifetime product, µτ, of 1.75 × 10−4 cm2 V−1, which renders the pellet with an X-ray sensitivity of 241.3 µC Gyair−1 cm−2 and a detection limit of 62 nGyair s−1 under 40 KVp X-ray illumination and 40 V bias voltage. The BiVO4 pellet also shows operational stability under steady X-ray illumination with total dose of 2.01 Gyair, equal to the dose of 20 000 medical chest X-ray inspections. This research reveals the potential application of BiVO4 in X-ray detection devices and inspires further research in this area.  相似文献   

8.
Transient optical spectroscopy is used to quantify the temperature-dependence of charge separation and recombination dynamics in P3TEA:SF-PDI2 and PM6:Y6, two non-fullerene organic photovoltaic (OPV) systems with a negligible driving force and high photocurrent quantum yields. By tracking the intensity of the transient electroabsorption response that arises upon interfacial charge separation in P3TEA:SF-PDI2, a free charge generation rate constant of ≈2.4 × 1010 s−1 is observed at room temperature, with an average energy of ≈230 meV stored between the interfacial charge pairs. Thermally activated charge separation is also observed in PM6:Y6, and a faster charge separation rate of ≈5.5 × 1010 s−1 is estimated at room temperature, which is consistent with the higher device efficiency. When both blends are cooled down to cryogenic temperature, the reduced charge separation rate leads to increasing charge recombination either directly at the donor-acceptor interface or via the emissive singlet exciton state. A kinetic model is used to rationalize the results, showing that although photogenerated charges have to overcome a significant Coulomb potential to generate free carriers, OPV blends can achieve high photocurrent generation yields given that the thermal dissociation rate of charges outcompetes the recombination rate.  相似文献   

9.
The charge transport properties of DNA are studied by the first-principle simulation to discuss the possibility of applying DNA to molecular wire. Both the hopping model and band-like model are introduced. By using hopping model, the theoretical hole mobilities calculated by Marcus theory between the same bases in DNA are 5.6 × 10−3, 4.1 × 10−2, 2.0 × 10−2 and 1.2 × 10−4 cm2V−1s−1 for T-T, A-A, C-C and G-G; and the calculated electron mobilities are 5.3 × 10−8, 1.5 × 10−4, 8.1 × 10−7 and 7.5 × 10−10 cm2V−1s−1 for T-T, A-A, C-C and G-G, respectively. And the charge transport for both holes and electrons between different bases exhibits directivity. By using band-like model, we calculated the band width of DNA with double helix structure and bilinear structure to investigate which structure will facilitate to the charge transport. We found that the band width of DNA increased when DNA transforming from the double helix structure to the bilinear structure, which means DNA with the bilinear structure possesses better charge transport properties. This research sheds a light on the molecular design for the molecule serving as the molecular wire.  相似文献   

10.
Fluorine doped tin oxide (FTO) films were fabricated on a glass substrate by a green sol–gel dip-coating process. Non-toxic SnF2 was used as fluorine source to replace toxic HF or NH4F. Effect of SnF2 content, 0–10 mol%, on structure, electrical resistivity, and optical transmittance of the films were investigated using X-ray diffraction, Hall effect measurements, and UV–vis spectra. Structural analysis revealed that the films are polycrystalline with a tetragonal crystal structure. Grain size varies from 43 to 21 nm with increasing fluorine concentration, which in fact critically impacts resultant electrical and optical properties. The 500 °C-annealed FTO film containing 6 mol% SnF2 shows the lowest electrical resistivity 7.0×10−4 Ω cm, carrier concentration 1.1×1021 cm−3, Hall mobility 8.1 cm2V−1 s−1, optical transmittance 90.1% and optical band-gap 3.91 eV. The 6 mol% SnF2 added film has the highest figure of merit 2.43×10−2 Ω−1 which is four times higher than that of un-doped FTO films. Because of the promising electrical and optical properties, F-doped thin films prepared by this green process are well-suited for use in all aspects of transparent conducting oxide.  相似文献   

11.
Sensitivity and detection limit of X-ray detectors are crucial for security checks, medical diagnoses, and industrial inspections. In this study, it is reported that introducing some cations containing lone-pair electrons is beneficial for enhancing the Compton scattering effect and thus improving X-ray detection performance. As an example, SnTe3O8 is selected and grown as a novel high-temperature X-ray detection crystal. Because of the high resistivity of 2 × 1014 Ω cm and high mobility lifetime product of 3.22 × 10−4 cm2 V−1, SnTe3O8 X-ray detector exhibits a high sensitivity of 436 µC Gyair−1 cm−2 under 120 keV hard X-ray, a low dark current drift of 2.44 × 10−9 nA cm−1 s−1 V−1 and a record low detection limit of 8.19 nGyair s−1 among all oxide X-ray detectors. Furthermore, the high-temperature sensitivity of SnTe3O8 X-ray detector is enhanced to 617 µC Gyair−1 cm−2 at 175 °C, which is ≈31 times larger than that of the commercial α-Se. The high thermal stability and stable high-temperature sensitivity of SnTe3O8 single crystal X-ray detectors have potential applications in high-temperature environments. The results not only provide an excellent high-temperature X-ray detection crystal but also propose an effective method to explore X-ray detector materials with excellent performances.  相似文献   

12.
2D InSe is one of the semimetal chalcogenides that has been recently given attention thanks to its excellent electrical properties, such as high mobility near 1000 cm2 V−1 s−1 and moderate band gap of ≈1.26 eV suitable for IR detection. Here, high-performance visible to near-infrared (470–980 nm wavelength (λ)) photodetectors using surface-doped InSe as a channel and few-layer graphenes (FLG) as electrodes are reported, where the InSe top region is relatively p-doped using AuCl3. The surface-doped InSe photodetectors show outstanding performance, achieving a photoresponsivity (R) of ≈19 300 A W−1 and a detectivity (D*) of ≈3 × 1013 Jones at λ = 470 nm, and R of ≈7870 A W−1 and D* of ≈1.5 × 1013 Jones at λ = 980 nm, superior to previously reported 2D material-based IR photodetectors operating without an applied gate bias. Surface doping using AuCl3 renders a band bending at the junction between the InSe surface and the top FLG contact, which facilitates electron-hole pair separation and immediate photodetection. Multiple doped or undoped InSe photodetectors with different device structures are investigated, providing insight into the photodetection mechanism and optimizing performance. Encapsulation with hexagonal boron nitride dielectric also allows for 3-month stability.  相似文献   

13.
Since transition metal dichalcogenide (TMD) semiconductors are found as 2D van der Waals materials with a discrete energy bandgap, many 2D‐like thin field effect transistors (FETs) and PN diodes are reported as prototype electrical and optoelectronic devices. As a potential application of display electronics, transparent 2D FET devices are also reported recently. Such transparent 2D FETs are very few in report, yet no p‐type channel 2D‐like FETs are seen. Here, 2D‐like thin transparent p‐channel MoTe2 FETs with oxygen (O2) plasma‐induced MoOx/Pt/indium‐tin‐oxide (ITO) contact are reported for the first time. For source/drain contact, 60 s short O2 plasma and ultrathin Pt‐deposition processes on MoTe2 surface are sequentially introduced before ITO thin film deposition and patterning. As a result, almost transparent 2D FETs are obtained with a decent mobility of ≈5 cm2 V?1 s?1, a high ON/OFF current ratio of ≈105, and 70% transmittance. In particular, for normal MoTe2 FETs without ITO, O2 plasma process greatly improves the hole injection efficiency and device mobility (≈60 cm2 V?1 s?1), introducing ultrathin MoOx between Pt source/drain and MoTe2. As a final device application, a photovoltaic current modulator, where the transparent FET stably operates as gated by photovoltaic effects, is integrated.  相似文献   

14.
Cu2ZnSnS4 (CZTS) is low cost and constitutes non-toxic materials abundant in the earth crust. Environment friendly solar cell absorber layers were fabricated by a thermal co-evaporation technique. Elemental composition of the film was stated by energy dispersive spectroscopy (EDS). Some optical and electrical properties such as absorption of light, absorption coefficient, optical band gap charge carrier density, sheet resistance and mobility were extracted. Optical band gap was found to be as 1.44 eV, besides, charge carrier density, resistivity and mobility were found as 2.14×1019 cm−3, 8.41×10−4 Ω cm and 3.45×102 cm2 V−1 s−1, respectively. In this study Ag/CZTS/n-Si Schottky diode was fabricated and basic diode parameters including barrier height, ideality factor, and series resistance were concluded using current–voltage and capacitance–voltage measurements. Barrier height and ideality factor values were found from the measurements as 0.81 eV and 4.76, respectively, for Ag/CZTS/n-Si contact.  相似文献   

15.
The dearth of suitable materials significantly restricts the practical development of infrared (IR) laser systems with highly efficient and broadband tuning. Recently, γ-NaAsSe2 is reported, and it exhibits a large nonlinear second-harmonic generation (SHG) coefficient of 590 pm V−1 at 2 µm. However, the crystal growth of γ-NaAsSe2 is challenging because it undergoes a phase transition to centrosymmetric δ-NaAsSe2. Herein, the stabilization of non-centrosymmetric γ-NaAsSe2 by doping the As site with Sb, which results in γ-NaAs0.95Sb0.05Se2 is reported. The congruent melting behavior is confirmed by differential thermal analysis with a melting temperature of 450 °C and crystallization temperature of 415 °C. Single crystals with dimensions of 3 mm × 2 mm are successfully obtained via zone refining and the Bridgman method. The purification of the material plays a significant role in crystal growth and results in a bandgap of 1.78 eV and thermal conductivity of 0.79 Wm−1 K−1. The single-crystal SHG coefficient of γ-NaAs0.95Sb0.05Se2 exhibits an enormous value of |d11| = 648 ± 74 pm V−1, which is comparable to that of γ-NaAsSe2 and ≈20× larger than that of AgGaSe2. The bandgap of γ-NaAs0.95Sb0.05Se2 (1.78 eV) is similar to that of AgGaSe2, thus rendering it highly attractive as a high-performing nonlinear optical material.  相似文献   

16.
ZnPc single-crystal nanobelts were grown by a physical vapor transport process with the length ranging from 20 to 150 μm and the width ranging from several tens of nanometers to several micrometers. Based on high crystalline ZnPc nanobelts, its single-crystal nanobelt transistors were realized. The field-effect mobility is as high as 0.75 cm2V−1s−1 with OTS modified SiO2 as dielectric, which is the highest value for the reported ZnPc devices. In addition, ZnPc nanobelt transistors show the excellently photosensitive properties with the high photoswitching ratio (|Ilight/Idark|) of 7.34 × 103 and the high photoresponsivity at 1.57 × 104 AW−1. These results indicate the future potential of ZnPc single-crystal transistors in organic electronic and optoelectronic applications.  相似文献   

17.
3D organic-inorganic metal halide perovskites are excellent materials for optoelectronic applications due to their exceptional properties, solution processability, and cost-effectiveness. However, the lack of environmental stability highly restricts them from practical applications. Herein, a stable centimeter-long 2D hybrid perovskite (N-MPDA)[PbBr4] single crystal using divalent N1-methylpropane-1,3-diammonium (N-MPDA) cation as an organic spacer, is reported. The as-grown single crystal exhibits stable optoelectronic performance, low threshold random lasing, and multi-photon luminescence/multi-harmonic generation. A photoconductive device fabricated using (N-MPDA)[PbBr4] single crystal exhibits an excellent photoresponsivity (≈124 AW−1 at 405 nm) that is ≈4 orders of magnitudes higher than that of monovalent organic spacer-assisted 2D perovskites, such as (BA)2PbBr4 and (PEA)2PbBr4, and large specific detectivity (≈1012 Jones). As an optical gain media, the (N-MPDA)[PbBr4] single crystal exhibits a low threshold random lasing (≈6.5 µJ cm−2) with angular dependent narrow linewidth (≈0.1 nm) and high-quality factor (Q ≈ 2673). Based on these results, the outstanding optoelectronic merits of (N-MPDA)[PbBr4] single crystal will offer a high-performance device and act as a dynamic material to construct stable future electronics and optoelectronic-based applications.  相似文献   

18.
Most doping research into transition metal dichalcogenides (TMDs) has been mainly focused on the improvement of electronic device performance. Here, the effect of self‐assembled monolayer (SAM)‐based doping on the performance of WSe2‐ and MoS2‐based transistors and photodetectors is investigated. The achieved doping concentrations are ≈1.4 × 1011 for octadecyltrichlorosilane (OTS) p‐doping and ≈1011 for aminopropyltriethoxysilane (APTES) n‐doping (nondegenerate). Using this SAM doping technique, the field‐effect mobility is increased from 32.58 to 168.9 cm2 V?1 s in OTS/WSe2 transistors and from 28.75 to 142.2 cm2 V?1 s in APTES/MoS2 transistors. For the photodetectors, the responsivity is improved by a factor of ≈28.2 (from 517.2 to 1.45 × 104 A W?1) in the OTS/WSe2 devices and by a factor of ≈26.4 (from 219 to 5.75 × 103 A W?1) in the APTES/MoS2 devices. The enhanced photoresponsivity values are much higher than that of the previously reported TMD photodetectors. The detectivity enhancement is ≈26.6‐fold in the OTS/WSe2 devices and ≈24.5‐fold in the APTES/MoS2 devices and is caused by the increased photocurrent and maintained dark current after doping. The optoelectronic performance is also investigated with different optical powers and the air‐exposure times. This doping study performed on TMD devices will play a significant role for optimizing the performance of future TMD‐based electronic/optoelectronic applications.  相似文献   

19.
The synthesis of organic electron-transport materials (ETMs) for organic light-emitting diodes (OLEDs) has been intensely pursued. Herein we report an organic phosphinyl compound (2,2′-Binaphthyl-6,6′-diyl)bis(diphenylphosphine oxide) (BiNa-BiDPO) with concise synthesis and purification. BiNa-BiDPO is thermally stable up to ca. 415 °C and exhibits distinct glass transition with a Tg of 112 °C after being cooled from the melt. Upon further heating, no crystallization or melting is observed. Ultraviolet photoemission spectroscopy studies reveal that EHOMO ≈ −6.12 eV for the new compound. Consequently, the LUMO level was roughly estimated as −2.77 eV based on the onset of the film absorption spectrum. BiNa-BiDPO possesses a higher electron mobility of 1.6–8.4 × 10−5 cm2 V−1 s−1 at E = 2–5 × 105 V cm−1, relative to a common ETM 1,3,5-tris(N-phenylbenzimidazolyl)benzene (TPBi), thus providing better OLED efficiency with lower working voltage. Moreover the OLED devices involving BiNa-BiDPO as the electron-transport layer showed a half life-time of 172 h at an initial luminance of ca. 1000 cd m−2, driven at a constant current density, in contrast with the TPBi device with a shortened t1/2 of 93 h. Further device engineering as well as molecular design may provide enhanced device durability.  相似文献   

20.
Photoexcited pyroelectricity in ferroelectrics allows the direct conversion of light radiation into electric signal without external power source, thus paving an avenue to promote optoelectronic device performances. However, it is urgently demanded to exploit new ferroelectrics with this attribute covering ultraviolet (UV)-to-infrared (IR) region for self-powered photodetection. Herein, broadband light-induced pyroelectric effects in a new 2D perovskite-type ferroelectric, (BBA)2(EA)2Pb3Br10 (1; BBA = p-bromobenzylammonium, EA = ethylammonium), showing a high Curie temperature of 425 K and notable pyroelectric coefficient (≈5.4 × 10−3 µC cm−2 K−1) is presented. Especially, photo-induced change of its electric polarization leads to ultraviolet-to-infrared pyroelectricity in a wide spectral region (377–1950 nm). Broadband photoactivities actualized by this property break the limitation of its optical bandgap. Thus, single-crystal detectors of 1 are sensitive to UV-to-IR light with a small temperature fluctuation of 0.3 K, exhibiting a high transient responsivity up to ≈0.28 mA W−1 and specific detectivity of 1.31 × 1010 Jones under zero bias (at 405 nm); such figure-of-merits are beyond than those self-powered photodetectors using oxide ferroelectrics. It is anticipated that the findings of light-induced pyroelectricity afford a feasible strategy to assemble newly-conceptual smart photoelectric devices, such as self-powered broadband detectors.  相似文献   

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