High-performance Photodetectors Research Articles

High-performance solar-blind photodetector based on amorphous BN in harsh environment operations

High-performance solar-blind photodetectors capable of operating in extreme environments are desirable for a wide range of applications, such as engine control, down hole drilling, space exploration, and environmental monitoring. Boron nitride (BN), with an ultrawide bandgap and high band edge absorption coefficient, is especially suitable for such application scenarios owing to its chemical and structural stability at high temperatures and radiative conditions, which, however, in turn, brings difficulties in synthesis of large-area continuous single crystalline BN. Here, we report highly robust solar-blind photodetectors based on amorphous BN (a-BN) films that can operate at high temperatures and high electric fields. The a-BN films are dense and uniform, grown at 500 °C using dual beam-assisted deposition method. The a-BN-based photodetectors exhibit high performance with a responsivity of 0.56 mA/W at 20 V under UV illumination of 222 nm and a high rejection ratio (R222 nm/R295 nm > 200 and R222 nm/R315 nm > 500). More importantly, these photodetectors demonstrate excellent responsivity and stability at high temperatures up to 500 K and high bias of 200 V without breakdown. The photocurrent mechanism at elevated temperatures is analyzed by temperature-dependent decay time of the temporal response, showing the electron–phonon interaction and self-trapped holes are dominant. Our work suggests that the deposition of such a-BN films offers a promising strategy toward highly environment-resistant solar-blind photodetectors.

Self-powered high-performance UV–vis–IR hybrid photovoltaic photodetector based on Epilobium angustifolium L. (Onagraceae)

Water-soluble Epilobium angustifolium (EA) extract was successfully coated on n-type Si single crystal by spin coating method to obtain EA/n-Si heterojunction device. UV–vis absorption and SEM analysis of the EA film were performed and the optical band gap was calculated as 2.71 eV. Electro-optical measurements of the fabricated device were performed and was found to give very good photoresponse in the UV–vis-IR regions. According to the experimental results, the EA/n-Si heterojunction showed not only high-performance photodetector properties but also self-driven properties under visible light as well as under UV and IR lights. At 150 mW/cm2 visible light, the device demonstrated excellent photovoltaic properties with Voc and Isc values of 0.40 V and 4.65 A, respectively. Under IR light, the responsivity, specific detectivity and NPDR reached 0.65 A/W and 1.41 × 1012 Jones, 4.23 × 108 W−1 respectively. Finally, a high-performance organic/inorganic photodetector in the broadband range has been successfully fabricated.

Toward Smart, Flexible, and Omnidirectional Self-Powered Photodetection by an All-Solution-Processed In2O3/Pbl2 Heterojunction.

Amorphous In2O3 film is emerging as a promising oxide semiconductor for next-generation electronics and optoelectronics owing to high mobility and wide band gap. However, the persistent photocurrent phenomenon and high carrier concentration in amorphous In2O3 film are challenging the photodetection performances, resulting in a long response time and low Ilight/Idark ratio. In this work, the In2O3/PbI2 heterojunction is constructed by an all-solution synthesis process to inhibit the persistent photocurrent phenomenon and large dark current. Benefiting from the built-in electric field at the heterojunction interface, the In2O3/PbI2 heterojunction photodetector exhibits excellent self-powered photodetection performances with an ultralow dark current of 10-12 A, a high Ilight/Idark ratio of 104, and fast response times of 0.6/0.6 ms. Furthermore, the entire solution synthesis process and amorphous characteristics enable the fabrication of an In2O3/PbI2 heterojunction photodetector on arbitrary substrates to realize specific functions. When configured onto the polyimide substrate, the In2O3/PbI2 heterojunction photodetector shows excellent mechanical flexibility, bending endurance, and photoresponse stability. When implanted onto the transparent substrate, the In2O3/PbI2 heterojunction photodetector exhibits an outstanding omnidirectional self-powdered photodetection performance and imaging capability. All results pave the way for an all-solution-processed amorphous In2O3 film in advanced high-performance photodetectors.

Cost-effective high-performance quantum dot photodetectors with dual polythiophene hole transporting layers

The strong aggregation of Poly(3-hexylthiophene) (P3HT) severely limits its use as the hole-transport material in emerging quantum dot photodetectors and photovoltaics. Herein, we propose a facile and cost-effective strategy to control the solution-state aggregation of hole transporting layers by designing a dual polythiophene blend based on P3HT and its alkylthio-substituted analogue named Poly(3-hexylthiothiophene) (P3HTT). In our photodetector device, we have used the dual polythiophene as the hole transport layer and achieved a specific detectivity (D*) on the order of 1012 Jones. In particular, by incorporating a small amount of P3HTT into the dual polythiophene mixture, we observed a remarkable 28% performance enhancement. This study provides a comprehensive analysis of the solution structure of the dual polythiophene blend, elucidates the evolution of the condensed matter structure, and ultimately presents a promising avenue for enhancing the performance of low-cost quantum dot photodetectors.

Boosted photothermoelectric effect in silver nanoparticles decorated carbon nanotube films for infrared detection and actuation

Photothermoelectric (PTE) effect provides a platform for utilization both photon and thermal energy, giving rise to high-performance photodetector and radiation energy harvester. Carbon nanotube (CNT)/metal heterojunction has been demonstrated to be capable of boosting power generation based on PTE effect, and yet the responsivity and detectivity are inferior to those based on conventional optoelectronic effect. Herein, CNT films decorated by Ag nanoparticles (NPs) forming Ag/CNT heterojunctions have been investigated, showing both excellent photothermal and power conversion capability under infrared (IR) illumination. Ultrahigh ΔT of 196.4 K, maximum output voltage of 15.74 mV and power of 9.94 μW have been achieved under IR laser illumination at power density of 7.65 W/cm2, which are superior to reported photodetectors based on PTE effect. CNT@Ag NPs film possesses competitive photodetection performance as well, with responsivity and detectivity of 107 mV/W and 947.68 MHz1/2/W, respectively. Furthermore, when integrated with polydimethylsiloxane, an IR laser actuated movement function mimicking caterpillar has been realized. Our study thus expands the diverse functions of CNT-based films utilizing PTE effect toward applications in IR detection, radiation energy harvesting and soft actuation.

Armchair zinc chalcogenide nanoribbons for high-performance photodetectors: A computational study

In this study, we employ density functional theory and non-equilibrium Green's function methods to investigate the electronic and photoelectric response properties of one-dimensional hexagonal ZnX (X = S, Se) nanoribbons (NRs). Remarkably, armchair (ARM) NRs demonstrate superior photoelectric response in the visible and near-ultraviolet regions. It is worth noting that for all considered photon energies, the photocurrent exhibits a cosine dependence on the polarization angle, which is consistent with the photogalvanic effect. when the width of NR is eight atoms, the zinc blende ZnSe/ARM NR-based device achieves a maximum extinction ratio of 63.9 at the photon energy of 3.0 eV. The significant photocurrent and high polarization sensitivity suggest the potential of ZnX NRs for applications in optoelectronic devices, particularly in visible and near-ultraviolet light detection.

A Self-Powered Broadband Photodetector with High Photocurrent Based on Ferroelectric Thin Film Using Energy Band Structure Design

Self-powered photodetectors have the advantages of high sensitivity, sustainability, and small size and have become a research hotspot in advanced optoelectronic systems. However, the low output photocurrent density seriously hinders the practical application of ferroelectric self-powered photodetectors. Herein, the high-efficiency photoelectric detection performance of the Bi1-xHoxFeO3 ferroelectric self-powered photodetector is realized by doping Ho. The responsivity (R) and detectivity (D*) can reach 0.0159 A/W and 1.94 × 1011 Jones under monochromatic light with a wavelength of 900 nm. Meanwhile, the R and D* can reach 0.022 A/W and 2.65 × 1011 Jones under sunlight. These excellent photodetection performances are attributed to the high short-circuit current density (Jsc). When the Ho content is 6%, the output photocurrent reaches up to 0.81 mA/cm2. The systematic structure and photo-electric characteristic analysis suggest that the decrease in the band gap leads to the generation of a larger photocurrent while the ferroelectric polarization is reduced slightly. This work provides a new way to obtain high-performance self-powered photodetectors.

Photogating enhanced photodetectors dominated by rubrene nanodots modified SnS2 films

The hybrid-induced photogating effect is considered as an effective way for photoconductance modulating in low-dimensional photodetectors. Besides, through constructing the local photogate vertical heterostructures on two-dimensional SnS2 surface can significantly increase its photoconductive gain. However, the potential of this photogain mechanism for SnS2 films has not yet been revealed in practical photodetection devices. To investigate its special advantages on promoting the optical-sensing activity, the high-quality SnS2 films with discrete, micro-area, and uniform rubrene-nanodots modification have been prepared. Benefit from the local interfacial photogating effect induced by hole trap states by rubrene-nanodots, the light-absorption and carrier-excitation efficiencies were significantly enhanced. Afterwards, the high-performance photodetector was designed based on the photogate vertical heterostructures of rubrene-nanodots/SnS2, which demonstrated an enhanced photoelectric response to 1064 nm light. Note that the maximum photocurrent density, photoresponsivity, and photodetectivity can reach up to 0.389 mA cm−2, 388.71 mA W−1, and 1.13 × 1010 Jones, respectively. Importantly, the optimal band-structure offsets accelerated the localized hole transfer from SnS2 film to rubrene-nanodots. The trapped holes in rubrene-nanodots induced an enhanced interface gating effect, which may help to modulate the number and lifetime of excess electrons under light illuminations. These superior features make the newly-developed photodetector be suitable for future multifunctional photodetection applications.

High performance self-powered solar-blind photodetector based on amorphous MgGa2O4/p-Si heterojunction

Self-powered solar-blind photodetectors are extensively implemented in military and industrial applications. Spinel ternary oxide MgGa2O4 with a wide bandgap of 4.92 eV is suitable for solar-blind photodetectors. Optoelectronic integration is a challenging research area, in terms of growing foreign semiconductors on Si substrates. Herein, a solar-blind photodetector based on amorphous MgGa2O4/p-Si heterojunction was fabricated by using RF magnetron sputtering. Under self-powered operation, the device exhibited good performance characteristics, including a high response sensitivity of 11.7 mA/W, a specific detectivity of 7.29 × 1011 Jones, and a fast photoresponse time (τr/τd = 0.200/0.021 s). This work demonstrates that the amorphous MgGa2O4/p-Si heterojunction is a promising approach to realize high-performance self-powered solar-blind photodetectors.

Element Diffusion Induced Carrier Transport Enhancement in High-Performance CZTSSe Self-Powered Photodetector.

Cu2ZnSn(S,Se)4 (CZTSSe) has attracted great interest in thin-film solar cells due to its excellent photoelectric performance in past decades, and recently is gradually expanding to the field of photodetectors. Here, the CZTSSe self-powered photodetector is prepared by using traditional photovoltaic device structure. Under zero bias, it exhibits the excellent performance with a maximum responsivity of 0.77 A W-1, a high detectivity of 8.78 × 1012 Jones, and a wide linear dynamic range of 103dB. Very fast response speed with the rise/decay times of 0.576/1.792 µs, and ultra-high switching ratio of 3.54 × 105 are obtained. Comprehensive electrical and microstructure characterizations confirm that element diffusion among ITO, CdS, and CZTSSe layers not only optimizes band alignment of CdS/CZTSSe, but also suppresses the formation of interface defects. Such a suppression of interface defects and spike-like band alignment significantly inhibit carrier nonradiative recombination at interface and promote carrier transport capability. The low trap density in CZTSSe and low back contact barrier of CZTSSe/Mo could be responsible for the very fast response time of photodetector. This work definitely provides guidance for designing a high performance self-powered photodetector with high photoresponse, high switching ratio, fast response speed, and broad linear dynamic range.

Visible-blind near-infrared organic photodetectors

The presently available commercial photodetectors have a broadband photoresponse and require different external optical filters to block the undesired light outside the detection spectrum window, e.g., near-infrared (NIR) detection. The use of an NIR bandpass has technical limitations in curved or flexible large-area photodetectors, as an NIR bandpass depends critically on the difference in the interference of the optical path in the filter. This work reports the effort to develop a high-performance filter-free organic photodetector (OPD) with a double bulk heterojunction (BHJ) structure. The visible-blind NIR photodetection is realized by eliminating the photocurrent generated in the front visible light-absorbing BHJ optical depletion layer, due to the suppression of electron transport by incorporating a copper thiocyanate-based electron-blocking layer in the OPD. Only excitons generated in the rear NIR-absorbing BHJ contribute to photocurrent in the OPD, thereby achieving visible-blind NIR photodetection. The double BHJ OPD has a high responsivity of 0.38 A/W at 1050 nm and a specific detectivity of >1013 Jones over the wavelength range from 800 to 1050 nm, making it an ideal candidate for applications in optical communication, food quality detection, wellness monitoring, and NIR image sensors.

Direct growth Bi2O2Se nanosheets on SiO2/Si substrate for high-performance and broadband photodetector

Bi2O2Se, a newly emerging two-dimensional (2D) material, has attracted significant attention as a promising candidate for optoelectronics applications due to its exceptional air stability and high mobility. Generally, mica and SrTiO3 substrates with lattice matching are commonly used for the growth of high-quality 2D Bi2O2Se. Although 2D Bi2O2Se grown on these insulating substrates can be transferred onto Si substrate to ensure compatibility with silicon-based semiconductor processes, this inevitably introduces defects and surface states that significantly compromise the performance of optoelectronic devices. Herein we employ Bi2Se3 as the evaporation source and oxygen reaction to directly grow Bi2O2Se nanosheets on Si substrate through a conventional chemical vapor deposition method. The photodetector based on the Bi2O2Se nanosheets on Si substrate demonstrates outstanding optoelectronics performance with a responsivity of 379 A W−1, detectivity of 2.9 × 1010 Jones, and rapid response time of 0.28 ms, respectively, with 532 nm illumination. Moreover, it also exhibits a broadband photodetection capability across the visible to near-infrared range (532–1300 nm). These results suggest that the promising potential of Bi2O2Se nanosheets for high-performance and broadband photodetector applications.

A high-performance and self-powered polarization-sensitive photoelectrochemical-type Bi2O2Te photodetector based on a quasi-solid-state gel electrolyte.

Among the two-dimensional (2D) Bi2O2X (X = S, Se, and Te) series, Bi2O2Te has the smallest effective mass and the highest carrier mobility. However, Bi2O2Te has rarely been investigated, most likely due to the lack of feasible methods to synthesize 2D Bi2O2Te. Herein, 2D Bi2O2Te nanosheets are successfully synthesized by low-temperature oxidation of Bi2Te3 nanosheets synthesized using a solvothermal method. The performance of a quasi-solid-state photoelectrochemical-type (PEC-type) photodetector based on 2D Bi2O2Te nanosheets is systematically investigated. Remarkably, the device has a high responsivity of 20.5 mA W-1 (zero bias) and fast rise/fall times of 6/90 ms under 365 nm illumination, which is superior to the majority of PEC-type photodetectors based on bismuth-based compounds. More importantly, due to the strong anisotropy of 2D Bi2O2Te nanosheets, the device achieves a dichroic ratio as high as 52, which belongs to the state-of-the-art polarized photodetectors. Besides, the capacity of 2D Bi2O2Te for high-resolution polarization imaging is demonstrated. This work provides a promising strategy for the synthesis of 2D Bi2O2Te nanosheets to fabricate a high-performance and polarization-sensitive photodetector.

High-performance self-powered ultraviolet photodetector based on a ZnO/CuPc inorganic/organic heterojunction.

A self-powered photodetector (PD) based on n-type ZnO/p-type small-molecule copper(ii) phthalocyanine (CuPc) inorganic/organic heterojunction film deposited on FTO substrate was constructed by simple solution spin-coating and thermal evaporation technology. The designed heterojunction device exhibits typical photoresponse behavior under zero bias, indicating that the device possesses a self-powered characteristic. This may benefit from the formation of a built-in electric field in the heterojunction, which can effectively separate electron-hole pairs. Specifically, the optimal performances of the device appear at a wavelength of 365 nm and light intensity of 0.03 mW cm-2, achieving on/off ratio of ∼245.88 (29.88), responsivity (Rp) of ∼227.11 mA W-1 (0.39 mA W-1), detectivity (D*) of ∼7.63 × 1011 Jones (∼7.53 × 109 Jones) and EQE of ∼77.23% (0.14%) at +2 V (0 V) bias voltage. In addition, the device has potential application in weak light detection. Therefore, the construction of inorganic/organic heterojunctions may provide a feasible strategy for the development of high-performance, self-powered and wavelength-selective PDs.

Asymmetric contact-induced selective doping of CVD-grown bilayer WS2 and its application in high-performance photodetection with an ultralow dark current.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are excellent candidates for high-performance optoelectronics due to their high carrier mobility, air stability and strong optical absorption. However, photodetectors made with monolayer TMDs often exhibit a high dark current, and thus, there is a scope for further improvement. Herein, we developed a 2D bilayer tungsten disulfide (WS2) based photodetector (PD) with asymmetric contacts that exhibits an exceptionally low dark current and high specific detectivity. High-quality and large-area monolayer and bilayer WS2 flakes were synthesized using a thermal chemical vapor deposition system. Compared to conventional symmetric contact electrodes, utilizing metal electrodes with higher and lower work functions relative to bilayer WS2 aids in achieving asymmetric lateral doping in the WS2 flakes. This doping asymmetry was confirmed through the photoluminescence spectral profile and Raman mapping analysis. With the asymmetric contacts on bilayer WS2, we find evidence of selective doping of electrons and holes near the Ti and Au contacts, respectively, while the WS2 region away from the contacts remains intrinsic. When compared with the symmetric contact case, the dark current in the WS2 PD with asymmetric (Au, Ti) contact decreases by an order of magnitude under reverse bias with a concomitant increase in the photocurrent, resulting in an improved on/off ratio of ∼105 and overall improved device performance under identical illumination conditions. We explained this improved performance based on the energy band alignment showing a unidirectional charge flow under light illumination. Our results indicate that the planar device structure and compatibility with current nanofabrication technologies can facilitate its integration into advanced chips for futuristic low-power optoelectronic and nanophotonic applications.

High-performance flexible photodetectors based on CdTe/MoS2 heterojunction.

Flexible photodetectors have attracted escalating attention due to their pivotal role in next-generation wearable optoelectronic devices. This work presents high-performance photodetector devices based on CdTe/MoS2 heterojunctions, showcasing outstanding photodetecting and distinctive mechanical properties. The MoS2 film was exfoliated from bulk layered MoS2 and covered by a sputtered ultrathin CdTe film (∼8.4 nm) to form a heterojunction. Benefitting from the photovoltaic effect induced by the built-in electrical field near the high-quality interface, the fabricated CdTe/MoS2 heterojunction photodetector can operate as a self-powered photodetector without any external bias voltage, especially showing a high photodetectivity of 5.84 × 1011 Jones, remarkable photoresponsivity of 270.3 mA W-1, fast photoresponse with a rise/fall time of ∼44.8/134.2 μs and excellent bending durability. These results demonstrate that the CdTe/MoS2 heterojunctions could have significant potential for future applications in optoelectronic devices.

Step-like 10-nm channel for high-performance PbS colloidal quantum dots near-infrared photodetector

The photodetector, featuring a 10-nm step-like channel, demonstrates a significantly improved responsivity of 23 A W−1 and an exceptionally high external quantum efficiency of 2800% upon spin-coating with PbS CQDs under 1000-nm illumination.

Sm, Pt asymmetric n- and p-type contacts in WSe2 phototransistor for high-performance broadband photodetection

The development of high-performance broadband photodetectors working at room temperature is still attractive. The Schottky barrier phototransistor based on asymmetric junction seems to be endowed with such potential—as photodetectors with low device power consumption and high photoresponse; however, it is rarely studied. Herein, a Sm–WSe2–Pt phototransistor with asymmetric metal contacts is constructed, and it is systematically investigated for their electronic and photoelectronic tunability via gate voltage, wavelength, and illumination power density. It was found that the tunable photogating process dominates the photoresponse mechanism, which allows for an excellent broadband photodetection from 300 to 1000 nm wavelength. In addition, the responsivity (R) and specific detectivity (D*) at 450 nm can reach 1723 A/W and 2.3 × 1013 Jones, respectively, while that of infrared illumination of 900 nm can reach 4.7 A/W and 3.1 × 1010 Jones, respectively. In addition, the device exhibits obvious photoresponse at zero bias, the R and D* can reach up to 27 mA/W and 8.5 × 1010 Jones, which realizes self-driven photodetection. This work provides an optimal option for realizing high-integrated, high-performance, low-power-consuming, and room-temperature-working broadband photodetectors.

A nanoflower-like GaSe/β-Ga2O3 based heterostructure for highly efficient self-powered broadband photodetectors

The combination of GaSe nanoflowers with β-Ga2O3 results in a high-performance heterojunction photodetector with self-powered operation and outstanding responsivity from deep UV to visible wavelengths.

Fabrication of Sb2Se3-based high-performance self-powered Visible-NIR broadband photodetector

Fabrication of Sb2Se3-based high-performance self-powered Visible-NIR broadband photodetector