High—Performance Solar‐Blind Deep Ultraviolet Photodetector Based on Individual Single‐Crystalline Zn2GeO4 Nanowire

Solar‐blind deep ultraviolet (DUV) photodetectors have been a hot topic in recent years because of their wide commercial and military applications. A wide bandgap (4.68 eV) of ternary oxide Zn₂GeO₄ makes it an ideal material for the solar‐blind DUV detection. Unfortunately, the sensing performance of previously reported photodetectors based on Zn₂GeO₄ nanowires has been unsatisfactory for practical applications, because they suffer from long response and decay times, low responsivity, and quantum efficiency. Here, high‐performance solar‐blind DUV photodetectors are developed based on individual single‐crystalline Zn₂GeO₄ nanowires. The transport mechanism is discussed in the frame of the small polaron theory. In situ electrical characterization of individual Zn₂GeO₄ nanowires reveals a high gain under high energy electron beam. The devices demonstrate outstanding solar‐blind light sensing performances: a responsivity of 5.11 × 10³ A W^?1, external quantum efficiency of 2.45 × 10⁶%, detectivity of ≈2.91 × 10¹¹ Jones, τ_rise ≈ 10 ms, and τ_decay ≈ 13 ms, which are superior to all reported Zn₂GeO₄ and other ternary oxide nanowire photodetectors. These results render the Zn₂GeO₄ nanowires particularly valuable for optoelectronic devices.     

Few‐Layered PtS2 Phototransistor on h‐BN with High Gain

The very recently rediscovered group‐10 transition metal dichalcogenides (TMDs) such as PtS₂ and PtSe₂, have joined the 2D material family as potentially promising candidates for electronic and optoeletronic applications due to their theoretically high carrier mobility, widely tunable bandgap, and ultrastability. Here, the first exploration of optoelectronic application based on few‐layered PtS₂ using h‐BN as substrate is presented. The phototransistor exhibits high responsivity up to 1.56 × 10³ A W^?1 and detectivity of 2.9 × 10¹¹ Jones. Additionally, an ultrahigh photogain ≈2 × 10⁶ is obtained at a gate voltage V _g = 30 V, one of the highest gain among 2D photodetectors, which is attributed to the existence of trap states. More interestingly, the few‐layered PtS₂ phototransistor shows a back gate modulated photocurrent generation mechanism, that is, from the photoconductive effect dominant to photogating effect dominant via tuning the gate voltage from the OFF state to the ON state. Such good properties combined with gate‐controlled photoresponse of PtS₂ make it a competitive candidate for future 2D optoelectronic applications.     

High Performance Ternary Organic Phototransistors with Photoresponse up to 2600 nm at Room Temperature

Infrared (IR) photodetection is important for light communications, military, agriculture, and related fields. Organic transistors are investigated as photodetectors. However, due to their large band gap, most organic transistors can only respond to ultraviolet and visible light. Here high performance IR phototransistors with ternary semiconductors of organic donor/acceptor complex and semiconducting single-walled carbon nanotubes (SWCNTs), without deep cooling requirements are developed. Due to both the ultralow intermolecular electronic transition energy of the complex and charge transport properties of SWCNTs, the phototransistor realizes broadband photodetection with photoresponse up to 2600 nm. Moreover, it exhibits outstanding performance under 2000 nm light with photoresponsivity of 2.75 × 10⁶ A W⁻¹, detectivity of 3.12 × 10¹⁴ Jones, external quantum efficiency over 10⁸%, and high I_photo/I_dark ratio of 6.8 × 10⁵. The device exhibits decent photoresponse to IR light even under ultra-weak light intensity of 100 nW cm⁻². The response of the phototransistor to blackbody irradiation is demonstrated, which is rarely reported for organic phototransistors. Interestingly, under visible light, the device can also be employed as synaptic devices, and important basic functions are realized. This strategy provides a new guide for developing high performance IR optoelectronics based on organic transistors.     

Fast,Self‐Driven,Air‐Stable,and Broadband Photodetector Based on Vertically Aligned PtSe2/GaAs Heterojunction

Group‐10 layered transitional metal dichalcogenides including PtS₂, PtSe₂, and PtTe₂ are excellent potential candidates for optoelectronic devices due to their unique properties such as high carrier mobility, tunable bandgap, stability, and flexibility. Large‐area platinum diselenide (PtSe₂) with semiconducting characteristics is far scarcely investigated. Here, the development of a high‐performance photodetector based on vertically aligned PtSe₂‐GaAs heterojunction which exhibits a broadband sensitivity from deep ultraviolet to near‐infrared light, with peak sensitivity from 650 to 810 nm, is reported. The I_light/I_dark ratio and responsivity of photodetector are 3 × 10⁴ and 262 mA W^?1 measured at 808 nm under zero bias voltage. The response speed of τ_r/τ_f is 5.5/6.5 µs, which represents the best result achieved for Group‐10 TMDs based optoelectronic device thus far. According to first‐principle density functional theory, the broad photoresponse ranging from visible to near‐infrared region is associated with the semiconducting characteristics of PtSe₂ which has interstitial Se atoms within the PtSe₂ layers. It is also revealed that the PtSe₂/GaAs photodetector does not exhibit performance degradation after six weeks in air. The generality of the above good results suggests that the vertically aligned PtSe₂ is an ideal material for high‐performance optoelectronic systems in the future.     

Ultra‐Thin Layered Ternary Single Crystals [Sn(SxSe1−x)2] with Bandgap Engineering for High Performance Phototransistors on Versatile Substrates

2D ternary semiconductor single crystals, an emerging class of new materials, have attracted significant interest recently owing to their great potential for academic interest and practical application. In addition to other types of metal dichalcogenides, 2D tin dichalcogenides are also important layered compounds with similar capabilities. Yet, multi‐elemental single crystals enable to assist multiple degrees of freedom for dominant physical properties via ratio alteration. This study reports the growth of single crystals Se‐doped SnS₂ or SnSSe alloys, and demonstrates their capability for the fabrication of phototransistors with high performance. Based on exfoliation from bulk high quality single crystals, this study establishes the characteristics of few‐layered SnSSe in structural, optical, and electrical properties. Moreover, few‐layered SnSSe phototransistors are fabricated on both rigid (SiO₂/Si) and versatile polyethylene terephthalate substrates and their optoelectronic properties are examined. SnSSe as a phototransistor is demonstrated to exhibit a high photoresponsivity of about 6000 A W^?1 with ultra‐high photogain ≈8.8 × 10⁵, fast response time ≈9 ms, and specific detectivity (D*) ≈8.2 × 10¹² J. These unique features are much higher than those of recently published phototransistors configured with other few‐layered 2D single crystals, making ultrathin SnSSe a highly qualified candidate for next‐generation optoelectronic applications.     

Efficient Assembly of Bridged β‐Ga2O3 Nanowires for Solar‐Blind Photodetection

An increasing number of applications using ultraviolet radiation have renewed interest in ultraviolet photodetector research. Particularly, solar‐blind photodetectors sensitive to only deep UV (<280 nm), have attracted growing attention because of their wide applicability. Among recent advances in UV detection, nanowire (NW)‐based photodetectors seem promising, however, none of the reported devices possesses the required attributes for practical solar‐blind photodetection, namely, an efficient fabrication process, a high solar light rejection ratio, a low photocurrent noise, and a fast response. Herein, the assembly of β‐Ga₂O₃ NWs into high‐performance solar‐blind photodetectors by use of an efficient bridging method is reported. The device is made in a single‐step chemical vapor deposition process and has a high 250‐to‐280‐nm rejection ratio (～2 × 10³), low photocurrent fluctuation (<3%), and a fast decay time (<<20 ms). Further, variations in the synthesis parameters of the NWs induce drastic changes in the photoresponse properties, which suggest a possibility for tuning the performance of the photodetectors. The efficient fabrication method and high performance of the bridged β‐Ga₂O₃ NW photodetectors make them highly suitable for solar‐blind photodetection.     

Integrating Efficient Optical Gain in High‐Mobility Organic Semiconductors for Multifunctional Optoelectronic Applications

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 (µ_h: 0.14 cm² V^?1 s^?1, µ_e: 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.     

MoS2/Si Heterojunction with Vertically Standing Layered Structure for Ultrafast,High‐Detectivity,Self‐Driven Visible–Near Infrared Photodetectors

As an interesting layered material, molybdenum disulfide (MoS₂) has been extensively studied in recent years due to its exciting properties. However, the applications of MoS₂ in optoelectronic devices are impeded by the lack of high‐quality p–n junction, low light absorption for mono‐/multilayers, and the difficulty for large‐scale monolayer growth. Here, it is demonstrated that MoS₂ films with vertically standing layered structure can be deposited on silicon substrate with a scalable sputtering method, forming the heterojunction‐type photodetectors. Molecular layers of the MoS₂ films are perpendicular to the substrate, offering high‐speed paths for the separation and transportation of photo‐generated carriers. Owing to the strong light absorption of the relatively thick MoS₂ film and the unique vertically standing layered structure, MoS₂/Si heterojunction photodetectors with unprecedented performance are actualized. The self‐driven MoS₂/Si heterojunction photodetector is sensitive to a broadband wavelength from visible light to near‐infrared light, showing an extremely high detectivity up to ≈10¹³ Jones (Jones = cm Hz^1/2 W^?1), and an ultrafast response speed of ≈3 μs. The performance is significantly better than the photodetectors based on mono‐/multilayer MoS₂ nanosheets. Additionally, the MoS₂/Si photodetectors exhibit excellent stability in air for a month. This work unveils the great potential of MoS₂/Si heterojunction for optoelectronic applications.     

All‐Layered 2D Optoelectronics: A High‐Performance UV–vis–NIR Broadband SnSe Photodetector with Bi2Te3 Topological Insulator Electrodes

Nanoelectronics is in urgent demand of exceptional device architecture with ultrathin thickness below 10 nm and dangling‐bond‐free surface to break through current physical bottleneck and achieve new record of integration level. The advance in 2D van der Waals materials endows scientists with new accessibility. This study reports an all‐layered 2D Bi₂Te₃‐SnSe‐Bi₂Te₃ photodetector, and the broadband photoresponse of the device from ultraviolet (370 nm) to near‐infrared (808 nm) is demonstrated. In addition, the optimized responsivity reaches 5.5 A W^?1, with the corresponding eternal quantum efficiency of 1833% and detectivity of 6 × 10¹⁰ cm Hz^1/2 W^?1. These figures‐of‐merits are among the best values of the reported all‐layered 2D photodetectors, which are several orders of magnitude higher than those of the previous SnSe photodetectors. The superior device performance is attributed to the synergy of highly conductive surface state of Bi₂Te₃ topological insulator, perfect band alignment between Bi₂Te₃ and SnSe as well as small interface potential fluctuation. Meanwhile, the all‐layered 2D device is further constructed onto flexible mica substrate and its photoresponse is maintained roughly unchanged upon 60 bending cycles. The findings represent a fundamental scenario for advancement of the next generation high performance and high integration level flexible optoelectronics.     

Single‐Crystalline p‐Type Zn3As2 Nanowires for Field‐Effect Transistors and Visible‐Light Photodetectors on Rigid and Flexible Substrates

Zn₃As₂ is an important p‐type semiconductor with the merit of high effective mobility. The synthesis of single‐crystalline Zn₃As₂ nanowires (NWs) via a simple chemical vapor deposition method is reported. High‐performance single Zn₃As₂ NW field‐effect transistors (FETs) on rigid SiO₂/Si substrates and visible‐light photodetectors on rigid and flexible substrates are fabricated and studied. As‐fabricated single‐NW FETs exhibit typical p‐type transistor characteristics with the features of high mobility (305.5 cm² V^?1 s^?1) and a high I_on/I_off ratio (10⁵). Single‐NW photodetectors on SiO₂/Si substrate show good sensitivity to visible light. Using the contact printing process, large‐scale ordered Zn₃As₂ NW arrays are successfully assembled on SiO₂/Si substrate to prepare NW thin‐film transistors and photodetectors. The NW‐array photodetectors on rigid SiO₂/Si substrate and flexible PET substrate exhibit enhanced optoelectronic performance compared with the single‐NW devices. The results reveal that the p‐type Zn₃As₂ NWs have important applications in future electronic and optoelectronic devices.     

A Noble Metal Dichalcogenide for High‐Performance Field‐Effect Transistors and Broadband Photodetectors

2D layered materials are an emerging class of low‐dimensional materials with unique physical and structural properties and extensive applications from novel nanoelectronics to multifunctional optoelectronics. However, the widely investigated 2D materials are strongly limited in high‐performance electronics and ultrabroadband photodetectors by their intrinsic weaknesses. Exploring the new and narrow bandgap 2D materials is very imminent and fundamental. A narrow‐bandgap noble metal dichalcogenide (PtS₂) is demonstrated in this study. The few‐layer PtS₂ field‐effect transistor exhibits excellent electronic mobility exceeding 62.5 cm² V^?1 s^?1 and ultrahigh on/off ratio over 10⁶ at room temperature. The temperature‐dependent conductance and mobility of few‐layer PtS₂ transistors show a direct metal‐to‐insulator transition and carrier scattering mechanisms, respectively. Remarkably, 2D PtS₂ photodetectors with broadband photodetection from visible to mid‐infrared and a fast photoresponse time of 175 µs at 830 nm illumination for the first time are obtained at room temperature. Our work opens an avenue for 2D noble‐metal dichalcogenides to be applied in high‐performance electronic and mid‐infrared optoelectronic devices.     

Monolayer Epitaxial Heterostructures for Selective Visible‐Light‐Driven Photocatalytic NO Oxidation

Construction of vertical heterostructures by stacking two‐dimensional (2D) layered materials via chemical bonds can be an effective strategy to explore advanced solar‐energy‐conversion systems. However, it remains a great challenge to fabricate such heterostructures based on conversional oxide‐based compounds, as they either do not possess a 2D layered structure or are not suitable for epitaxial growth due to large lattice mismatch. Here, a vertical heterostructure of bismuth oxyhalide semiconductors fabricated through a heteroepitaxial anion exchange method is reported. Monolayer Bi₂WO₆ is epitaxially grown on the exposed surface of BiOI to inhibit photocorrosion and introduce active sites. Theoretical and experimental results reveal that electrons generated under visible‐light irradiation can directly transfer to surface coordinatively unsaturated (CUS) Bi atoms, which contribute to the adsorption and activation of reactant molecules. As a result, the Bi₂WO₆/BiOI vertical heterostructures exhibit significantly enhanced visible‐light‐driven NO oxidation activity compared with BiOI and Bi₂WO₆.     

Ternary Ta2NiSe5 Flakes for a High‐Performance Infrared Photodetector

Multielemental systems enable the use of multiple degrees of freedom for control of physical properties by means of stoichiometric variation. This has attracted extremely high interest in the field of 2D optoelectronics in recent years. Here, for the first time, multilayer 2D ternary Ta₂NiSe₅ flakes are successfully fabricated using a mechanical exfoliation method from chemical vapor transport synthesized high quality bulk and the optoelectronic properties are systematically investigated. Importantly, a high responsivity of 17.21 A W^?1 and high external quantum efficiency of 2645% are recorded from an as‐fabricated photodetector at room temperature in air; this is superior to most other 2D materials‐based photodetectors that have been reported. More intriguingly, a usual sublinear and an unusual superlinear light‐intensity‐dependent photocurrent are observed under air and vacuum, respectively. These excellent and special properties make multilayer ternary Ta₂NiSe₅ a highly competitive candidate for future infrared optoelectronic applications and an interesting platform for photophysics studies.     

Bandgap Engineering of BiIns Nanowire for Wide-Spectrum,High-Responsivity,and Polarimetric-Sensitive Detection

Optical devices based on alloying semiconductors offer a plethora of new possibilities for detection across a broad spectrum. Among these devices, nanowire-based devices have gained much attention due to their remarkable specific surface area properties in terms of material synthesis, device structure, and performance. In this work, (Bi_xIn_1−x)₂S₃ nanowires are designed by controlling the ratio of Bi and In atoms. The atomic ratio directly affects the electronic band structure of the crystal, thereby further optimizing the performance of optoelectronic devices. According to the experimental results, Bi_1.28In_0.72S₃ nanowire-based photodetectors obtain the most excellent photoresponse performance. The typical device demonstrates a spectral response from deep ultraviolet (DUV 254 nm) to near-infrared (NIR 1064 nm) and achieves a maximum dichroic ratio of photoresponse of 1.5 under polarization-angle-sensitive detection in the 266–808 nm range. It also exhibits a photoresponse of 10.1 A W⁻¹ and a photodetectivity of 5.7 × 10¹⁰ Jones under 532 nm light irradiation. Additionally, the photodetector displays a fast response speed with a rise/fall time of 5/4.7 ms. Finally, “CSU” and puppy images produced by this device further demonstrate the effectiveness of alloying semiconductors in creating wide-spectrum, high-responsivity, fast-response, and polarimetric-sensitive photodetectors.     

Machine Vision Based on an Ultra-Wide Bandgap 2D Semiconductor AsSbO3

Facing the future development trend of miniaturization and intelligence of electronic devices, solar-blind photodetectors based on ultrawide-bandgap 2D semiconductors have the advantages of low dark current, and high signal-to-noise ratio, as well as the features of micro-nanometer miniaturization and multi-functionalization of 2D material devices, which have potential applications in the photoelectric sensor part of high-performance machine vision systems. This study reports a 2D oxide semiconductor, AsSbO₃, with an ultrawide bandgap (4.997 eV for monolayer and 4.4 eV for multilayer) to be used to fabricate highly selective solar-blind UV photodetectors, of which the dark current as low as 100 fA and rejection ratio of UV-C and UV-A reaches 7.6 × 10³. Under 239 nm incident light, the responsivity is 105 mA W⁻¹ and the detectivity is 7.58 × 10¹² Jones. Owing to the remarkable anisotropic crystal structure, AsSbO₃ also shows significant linear dichroism and nonlinear optical properties. Finally, a simple machine vision system is simulated by combining the real-time imaging function in solar-blind UV with a convolutional neural network. This study enriches the material system of ultrawide-bandgap 2D semiconductors and provides insight into the future development of high-performance solar-blind UV optoelectronic devices.     

Air-Stable Self-Powered Photodetectors Based on Lead-Free CsBi3I10/SnO2 Heterojunction for Weak Light Detection

Lead halide perovskites (LHPs) have been widely investigated in photodetection applications owing to their intriguing optoelectronic properties. However, the application of LHPs-based photodetectors (PDs) is hindered because of the toxicity of lead and instability in ambient air. Here, an air-stable self-powered photodetector is designed based on all-inorganic lead-free CsBi₃I₁₀/SnO₂ heterojunction. The device exhibits broad spectral response in both UV and visible light, fast response on µs scale, and decent long-term stability. The device holds a faster response speed (t_r/t_d = 7.8/8.8 µs), among the best reported self-powered lead-free perovskites photodetectors. More importantly, the device can display obvious photoresponses even under ultra-weak light intensity as low as 10 pW cm^–2, showing better weak-light sensitivity than previously reported lead-free perovskites photodetectors, to the best of our knowledge. Moreover, the device holds good air stability in the 73 days test without encapsulation. These results suggest that CsBi₃I₁₀/SnO₂-based self-powered PDs with high photodetection capability possess enormous potential in stable and broadband PDs for weak light detection in the future.     

Mixed‐Dimensional 1D ZnO–2D WSe2 van der Waals Heterojunction Device for Photosensors

2D layered van der Waals (vdW) atomic crystals are an emerging class of new materials that are receiving increasing attention owing to their unique properties. In particular, the dangling‐bond‐free surface of 2D materials enables integration of differently dimensioned materials into mixed‐dimensional vdW heterostructures. Such mixed‐dimensional heterostructures herald new opportunities for conducting fundamental nanoscience studies and developing nanoscale electronic/optoelectronic applications. This study presents a 1D ZnO nanowire (n‐type)–2D WSe₂ nanosheet (p‐type) vdW heterojunction diode for photodetection and imaging process. After amorphous fluoropolymer passivation, the ZnO–WSe₂ diode shows superior performance with a much‐enhanced rectification (ON/OFF) ratio of over 10⁶ and an ideality factor of 3.4–3.6 due to the carbon–fluorine (C? F) dipole effect. This heterojunction device exhibits spectral photoresponses from ultraviolet (400 nm) to near infrared (950 nm). Furthermore, a prototype visible imager is demonstrated using the ZnO–WSe₂ heterojunction diode as an imaging pixel. To the best of our knowledge, this is the first demonstration of an optoelectronic device based on a 1D–2D hybrid vdW heterojunction. This approach using a 1D ZnO–2D WSe₂ heterojunction paves the way for the further development of electronic/optoelectronic applications using mixed‐dimensional vdW heterostructures.     

Photoresponsive Transistors Based on Lead‐Free Perovskite and Carbon Nanotubes

Lead‐free perovskite materials are exhibiting bright application prospects in photodetectors (PDs) owing to their low toxicity compared with traditional lead perovskites. Unfortunately, their photoelectric performance is constrained by the relatively low charge conductivity and poor stability. In this work, photoresponsive transistors based on stable lead‐free bismuth perovskites CsBi₃I₁₀ and single‐walled carbon nanotubes (SWCNTs) are first reported. The SWCNTs significantly strengthen the dissociation and transportation of the photogenerated charge carriers, which lead to dramatically improved photoresponsivity, while a decent I_light/I_dark ratio over 10² can be maintained with gate modulation. The devices exhibit high photoresponsivity (6.0 × 10⁴ A W^?1), photodetectivity (2.46 × 10¹⁴ jones), and external quantum efficiency (1.66 × 10⁵%), which are among the best reported results in lead‐free perovskite PDs. Furthermore, the excellent stability over many other lead‐free perovskite PDs is demonstrated over 500 h of testing. More interestingly, the device also shows the application potential as a light‐stimulated synapse and its synaptic behaviors are demonstrated. In summary, the lead‐free bismuth perovskite‐based hybrid phototransistors with multifunctional performance of photodetection and light‐stimulated synapse are first demonstrated in this work.     

Tailoring of Silver Nanocubes with Optimized Localized Surface Plasmon in a Gap Mode for a Flexible MoS2 Photodetector

Although noble metal nanoparticles as nanoantenna have been applied in 2D material‐based optoelectronic devices, the impact of their morphologies on device performance is still rarely investigated. In this paper, the tailoring of silica‐coated Ag nanocubes with optimized localized surface plasmon in a gap mode for a flexible MoS₂ photodetector is demonstrated for the first time. The finite different time domain simulation reveals that the Ag nanocubes with an edge length of 60 nm achieve a maximum electromagnetic field enhancement of 2.8 × 10⁶‐fold under excitation of 520 nm incident light, which is about four orders of magnitude higher than that of Ag nanospheres and nanorods. The Ag nanocube modified devices exhibit excellent performance at low operating potential. External photoresponsivity reaches 7940 A W^?1 at 3 V under an incident power of 2.2 pW, achieving a 38‐fold enhancement compared to the pristine MoS₂ photodetector, which is more than one order of magnitude higher than most of the reported MoS₂ photodetectors. The flexible devices also display a good mechanical endurance during 10 000 bending cycles. These results indicate that Ag nanocubes coupled with Ag films show great prospect for their application in the field of 2D material‐based optoelectronic devices.     

Ultrahigh Stability 3D TI Bi2Se3/MoO3 Thin Film Heterojunction Infrared Photodetector at Optical Communication Waveband

Infrared (IR) detection at 1300–1650 nm (optical communication waveband) is of great significance due to its wide range of applications in commerce and military. Three dimensional (3D) topological insulator (TI) Bi₂Se₃ is considered a promising candidate toward high‐performance IR applications. Nevertheless, the IR devices based on Bi₂Se₃ thin films are rarely reported. Here, a 3D TI Bi₂Se₃/MoO₃ thin film heterojunction photodetector is shown that possesses ultrahigh responsivity (R_i), external quantum efficiency (EQE), and detectivity (D*) in the broadband spectrum (405–1550 nm). The highest on–off ratio of the optimized device can reach up to 5.32 × 10⁴. R_i, D*, and the EQE can reach 1.6 × 10⁴ A W^?1, 5.79 × 10¹¹ cm² Hz^1/2 W^?1, and 4.9 × 10⁴% (@ 405 nm), respectively. Surprisingly, the R_i can achieve 2.61 × 10³ A W^?1 at an optical communication wavelength (@ 1310 nm) with a fast response time (63 µs), which is two orders of magnitude faster than that of other TIs‐based devices. In addition, the device demonstrates brilliant long‐term (>100 days) environmental stability under environmental conditions without any protective measures. Excellent device photoelectric properties illustrate that the 3D TI/inorganic heterojunction is an appropriate way for manufacturing high‐performance photodetectors in the optical communication, military, and imaging fields.