Self-powered Broadband Research Articles

Self-Powered Broadband Photodetector and Sensor Based on Novel Few-Layered Pd3(PS4)2 Nanosheets.

Optoelectronics and sensing devices are of enormous importance in our modern lives, which has propelled the scientific community to explore new two-dimensional (2D) nanomaterials to meet the requirements of future devices. Herein, we present the exfoliation of palladium thiophosphate (Pd3(PS4)2) by mechanical shear force exfoliation. The Pd3(PS4)2-based photoelectrochemical (PEC) device demonstrated self-powered broadband photodetection in the range of 385-940 nm with an unprecedented responsivity of 2 A W-1 and a specific detectivity of about 8.67 × 1011 cm Hz1/2 W-1 under the illumination of 420 nm LED light. The crucial parameters such as photoresponsivity, response, and recovery time of the device can be controlled by an externally applied voltage and the analyte concentration. Moreover, Pd3(PS4)2-based vapor-sensing devices exhibited frequency-dependent selective acetone sensing in the presence of other organic vapors with an ultrafast response and a recovery time of less than 1 s. Finally, the photocatalytic activity of Pd3(PS4)2 was revealed, which can be attributed to the presence of an appropriate band alignment with the catalytic activity of Pd. This novel material with the aforementioned fascinating phenomenon will pave the way toward practical future applications in optoelectronics and sensing.

Pentacene and CuO Nanocomposite Based Self-Powered Broadband Photodetector

This work proposes an Al/Pentacene:CuO/ PEDOT:PSS/ITO structure based photodetector fabricated on an indium-tin oxide (ITO) coated glass substrate by low-cost solution method. The device uses Pentacene:CuO nanocomposite as the active layer and PEDOT:PSS as the hole transport layer (HTL). The proposed device shows a broadband photodetection properties with responsivities of ~35.25 A/W, ~8.74 A/W and ~2.75 A/W at wavelengths of ~380 nm (UV), ~600 nm (visible) and ~980 nm (NIR) under 1 V reverse bias voltage, respectively. The device also shows the self-biased property with the maximum responsivity of ~14.4 mA/W at ~600 nm under zero bias operation. The repeatability and stability of the device have been observed through repetitive device fabrication with subsequent measurements.

Enhanced Light Trapping in Conformal CuO/Si Microholes Array Heterojunction for Self-Powered Broadband Photodetection

In this letter, we demonstrate the fabrication of a conformal CuO/Si microholes array heterojunction through the DC reactive magnetron sputtering from a high-purity Cu target. By using the monolayer graphene as the top electrode, the device served well as a self-powered vis-NIR photodetector, showing a high responsivity of 301.5 mA W <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , specific detectivity of 7.96×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones and a fast response speed (rise time 9.9 μ s and fall time 10 μs) upon 530 nm illumination. Compared to its planar counterpart, the responsivity was remarkably enhanced over the broadband region. The underlying reason should be ascribed to the improved light trapping in the microholes via the longitudinal Fabry-Perot (F-P) cavity resonance, according to theoretical simulation by finite-difference time-domain (FDTD) solution. Such an effect gave rise to an enhanced light-matter interaction, leading to the improved photoresponse. This work also opens up an effective way for the on-chip high performance photodetection due to the well compatibility with the current complementary metal-oxide-semiconductor (CMOS) technology.

MAPbI3-based efficient, transparent and air-stable broadband photodetectors

Numerous structures have been reported in search of affordable self-powered broadband photodetectors, however with limited success. The hybrid perovskite heterostructures have been attracted great attention due to their advance optical and electrical properties. The stability and facile synthesis are critical issues in achieving the potential success of realizing perovskite-based photodetectors. Herein, we report a facile one-step spray-coated method to synthesize MAPbI3 perovskite polycrystalline thin-film on the glass as photodetector followed by their morphological (Atomic force microscopy), structural (X-ray diffraction/Fourier transform infrared spectroscopy, optical (UV–Vis), and electrical characterization. The device shows a very good response for visible and NIR region with the responsivity, detectivity, and external quantum efficiency of 1.682 mA/W, 1.5065 × 1012 Jones, and 0.3799, respectively. Further, the device exhibits photoresponse under visible to IR (400–900 nm) light illuminations, which holds great futuristic promises for affordable, broadband, stable, and efficient energy-conserving electronics.

Self-powered broadband hybrid organic–inorganic photodetectors based on PEDOT:PSS and silicon micro-nanostructures

Structural modifications to the surface of the active layer of hybrid organic-inorganic self-powered broadband photodetectors lead to a remarkable enhancement in their photoresponse.

Self-powered broadband photodetector based on a solution-processed p-NiO/n-CdS:Al heterojunction

Solution-processed photodetectors have emerged as the next generation of sensing technology owing to their ease of integration with electron devices and of tuning photodetector performance. Currently, novel self-powered photodetectors without an external power source, for use in sensing, imaging and communication, are in high demand. Herein, we successfully developed a self-powered photodetector based on a novel solution-processed p-NiO/n-CdS:Al heterojunction, which shows an excellent current rectification characteristic ratio of up to three orders in the dark and distinctive photovoltaic behavior under light illumination. The complete solution synthesis route followed the development of CdS:Al thin films on ITO substrates by chemical bath deposition and NiO thin films by the sol-gel route. Optical absorption data revealed that NiO is more active in the UV region and CdS:Al has a majority of absorption in the visible region; so, upon light illumination, the effective separation of photogenerated carriers produces fast photodetection in the UV–visible region. The photoresponsivity values of the fabricated device were calculated to be 55 mA W−1 and 30 mA W−1 for UV and visible illumination, respectively. Also, the device has a fast rise and decay photoresponse speed at zero bias voltage, due to the self-driven photovoltaic effect which makes this heterojunction a self-powered device. This complete solution and new method of fabrication make it possible to combine different materials and flexible substrates, enhancing its potential applications in photodetectors, optoelectronic devices and sensors.

A high performance self-powered heterojunction photodetector based on NiO nanosheets on an n-Si (1 0 0) modified substrate

A self-powered ultraviolet–visible photodetector based on NiO/Si heterojunctions made from NiO nanosheets on a Si (100) modified substrate was successfully manufactured via a facile hydrothermal method and subsequent calcination process. The fabricated detectors not only response to ultraviolet (UV) and visible light, but also possess excellent photocurrents and a lower dark current. The good performance, i.e., the external quantum efficiency (EQE) of ~22.4% and 33.1% under 350 nm and 600 nm, respectively, at zero bias, superior to most reported NiO/Si photodetectors, could be ascribed to the good crystalline NiO nanosheets and the suitable n-Si (100) substrate. Therefore, as-fabricated self-powered broadband detectors have a great potential application in wearable and portable devices.

Self-powered ultraviolet–visible–near infrared perovskite/silicon hybrid photodetectors based on a novel Si/SnO2/MAPbI3/MoO3 heterostructure

We developed a self-powered broadband perovskite/silicon hybrid photodetector based on a novel heterostructure of Si/SnO2/MAPbI3/MoO3. The insertion of SnO2 and MoO3 was effective in reducing the recombination of photogenerated carriers. By optimizing the thickness of the SnO2 layer, the detection capabilities of the hybrid photodetectors were significantly improved. The best-performing photodetector had a 40 nm SnO2 layer, showing a detectivity of 2.23 × 1012 Jones with a responsivity of 50.9 mA W−1 at 815 nm and a photocurrent/dark current ratio of 3.37 × 104 under zero bias. Furthermore, the photodetectors were sensitive to broadband irradiation from 300 to 1150 nm.

Self-Powered Broadband Photodetector Based on Single-Walled Carbon Nanotube/GaAs Heterojunctions

Van der Waals (vdW) heterojunctions between single-walled carbon nanotubes (SWCNTs) and GaAs are potential candidates for optoelectronic devices owing to their direct bandgap, high carrier mobility...

Self-powered broadband photo-detection and persistent energy generation with junction-free strained Bi2Te3 thin films.

We experimentally demonstrate efficient broadband self-powered photo-detection and power generation in thin films of polycrystalline bismuth telluride (Bi2Te3) semiconductors under inhomogeneous strain. The developed simple, junction-free, lightweight, and flexible photo-detectors are composed of a thin active layer and Ohmic contacts on a flexible plastic substrate, and can operate at room temperature and without application of an external bias voltage. We attribute the observed phenomena to the generation of an electric field due to a spontaneous polarization produced by strain gradient, which can separate both photo-generated and thermally-generated charge carriers in bulk of the semiconductor material, without a semiconductor junction. We show that the developed photo-detectors can generate electric power during both the daytime and the nighttime, by either harnessing solar and thermal radiation or by emitting thermal radiation into the cold sky. To the best of our knowledge, this is the first demonstration of the power generation in a simple junction-free device under negative illumination, which exhibits higher voltage than the previously used expensive commercial HgCdTe photo-diode. Significant improvements in the photo-detector performance are expected if the low-charge-mobility polycrystalline active layer is replaced with high-quality single-crystal material. The technology is not limited to Bi2Te3 as the active material, and offers many potential applications in night vision, wearable sensors, long-range LIDAR, and daytime/nighttime energy generation technologies.

Self-powered broadband photodetection using PbS decorated ZnO nanorods/reduced graphene oxide junction

Vertically aligned ZnO nanorods (NRs) were grown on fluorine doped tin oxide (FTO) coated glass substrates using hydrothermal method. Self-powered broadband photodetector was fabricated with PbS decorated ZnO NRs and reduced graphene oxide (RGO) junction. ZnO NRs/PbS/RGO device demonstrated significant photocurrent over broad spectral range 350–700 nm. Our photodetector showed maximum external quantum efficiency (EQE) ~78%, responsivity Rλ ~0.25A/W and detectivity (Dλ ) ~82944.55Hz1/2/W at 400 nm under zero bias. The transient photoresponse of the device exhibited fast response (~65 ms) and recovery time (~74 ms). Such PbS/ZnO NRs p-n heterojunction also demonstrated photovoltaic properties with open circuit voltage (VOC) ~ 0.27 V, short circuit current (JSC) ~1.03 mA/cm2 and power conversion efficiency (PEC) ~0.73% under illumination of white light of intensity 100 mW/cm2.

Enhanced performances of p-si/n-ZnO self-powered photodetector by interface state modification and pyro-phototronic effect

ZnO based self-powered photodetector (PD) has great application potential in distributing sensor networks and internet of things. However, a large number of surface or interface states within ZnO limit its performance improvement. Here, the surface and interface states of ZnO is greatly eliminated by ultraviolet irradiation as an interfacial modification engineering. Reduction of interface states reduces ohmic resistance, also enhances the tuning role of pyro-phototronic effect. And the transient response currents of the self-powered PD are thus significantly improved with a maximal enhancement factor of more than 5900% for the 325–785 nm broadband stimulating beams. The corresponding response time is decreased to few milliseconds or sub-milliseconds. The results indicate that surface-state reduction of ZnO can effectively enhance the modifying role of pyro-phototronic effect and greatly improve the response performances of the self-powered broadband PDs with great application demands in Internet of things, broad spectral detecting and imaging, and smart optoelectronic devices.

Graphene/GaAs heterojunction for highly sensitive, self-powered Visible/NIR photodetectors

Graphene/GaAs heterojunction has been demonstrated by transferring monolayer graphene on the surface of n-GaAs substrate, and the carrier transfer at the interface has been investigated by monitoring Raman shift of graphene on different substrates. The photovoltaic behavior and rectifying characteristic of the graphene/GaAs heterojunctions enable us to fabricate high-performance self-powered photodetector at zero bias. The device has been demonstrated to be sensitive to visible/near-infrared light (405–850 nm) at room temperature, giving rise to maximum responsivity of 122 mA W−1 and detectivity of 4.3 × 1012 Jones with quick response and recover time (0.5 ms and 0.35 ms), respectively. Such high photoelectric response is attributed to the efficient photo-generated carrier separation and transfer at the interface, which is caused by the strong built-in electric field between grapheme and GaAs because of a large barrier (0.87 eV). Our results confirm that the graphene/GaAs heterojunction has a great potential for high performance self-powered broadband photodetectors.

See-through metal oxide frameworks for transparent photovoltaics and broadband photodetectors

In this work, we report metal-oxide based fast and stable transparent self-powered broadband (UV to NIR) photovoltaic devices. Using sputtering technique, we prepared the large-scale and transparent metal-oxide heterojunction device by formation of p-Cu-Cu2O/n-ZnO films on a FTO glass substrate. The heterojunction of Cu–Cu2O/ZnO is invisible to human eyes due to its high energy bandgap to render high transparency (>80%) for long wavelength light within the range 600–1100 nm. Meanwhile, it strongly absorbs short wavelength of UV light (below 400 nm), which may cause hurts to human eyes or skin cancers.The transparent Cu–Cu2O/ZnO device is the invisible electric power generator due to photovoltaic behaviour with the open-circuit-voltage of 0.36 V and high short-circuit-current value (1.83 mA), resulting in the maximum conversion efficiency of 0.405%. In addition, the transparent Cu–Cu2O/ZnO photovoltaic device also works as the self-operating photodetector. In the photovoltaic mode, Cu–Cu2O/ZnO heterojunction provided the fast and stable photoresponse (rise time ~3.89 ms and decay time ~4.12 ms) towards white light which is considered to be the fastest performance of Cu2O/ZnO based thin film photodetectors.These results represent a significant advancement in the see-through photovoltaic device with low-cost and evidently high efficiency. We may consider the transparent window as a power generator to provide electric energy on-demand sites, such as buildings, houses, or vehicles, while protected from the harmful UV radiation due to the smart functioning window.

Enhanced Photodetection Properties of Tellurium@Selenium Roll-to-Roll Nanotube Heterojunctions.

Non-layered tellurium (Te) is a promising material for applications in transistor and optoelectronic devices for its advantages in excellent intrinsic electronic and optoelectronic properties. However, the poor photodetection performance and relatively uncertain stability of tellurene under ambient conditions greatly limit the practical applications. In order to improve the performance of tellurene-based materials, Te@Se roll-to-roll nanotubes with different selenium (Se) contents synthesized by epitaxial growth of Se on Te nanotubes are, for the first time, employed to fabricate working electrodes for photoelectrochemical (PEC)-type broadband photodetection. They exhibit not only a preferably enhanced capacity for self-powered broadband photodetection but also significantly improved photocurrent density and stability in various aqueous environments (HCl, NaCl, and KOH solutions), compared to tellurene-based photodetectors. It is anticipated that the present work can open up new possibilities for high-performance tellurene-based optoelectronic devices.

Self-Powered Broadband (UV-NIR) Photodetector Based on 3C-SiC/Si Heterojunction

Self-powered photodetectors (PDs) are highly desirable for many applications, ranging from smart cities to optical communications. Herein, we report on a self-powered broadband [UV to near-infrared (NIR)] PD based on a single-crystalline SiC (100)/Si (100) heterojunction. In self-powered photovoltaic detection mode, the detector exhibits a high responsivity (2500 V/W at $\text {8.0} \times \text {10}^{\text {-6}}$ W/cm2, 521 nm) and specific detectivity (~1013 Jones at $8.0 \times 10^{-6}$ W/cm2, 521 nm) under UV, visible, and NIR spectral illuminations thanks to the superior rectification property of the heterojunction which results in significantly reducing the dark current. The device also shows high illumination ON/ OFF switching ratios, as high as $\text {2.2} \times \text {10}{^{\text {7}}}$ , with an excellent stability and repeatability. A detailed insight about electron–hole pairs generation, separation, and Fermi-energy level shifting at different illumination conditions has been elucidated via energy band diagrams.

In Situ Fabrication of 2D WS2/Si Type-II Heterojunction for Self-Powered Broadband Photodetector with Response up to Mid-Infrared

The high-performance broadband photodetectors have attracted intensive scientific interests due to their potential applications in optoelectronic systems. Despite great achievements in two-dimensional (2D) materials based photodetectors such as graphene and black phosphorus, obvious disadvantages such as low optical absorbance and instability preclude their usage for the broadband photodetectors with the desired performance. An alternative approach is to find promising 2D materials and fabricate heterojunction structures for multifunctional hybrid photodetectors. In this work, 2D WS2/Si heterojunction with a type-II band alignment is formed in situ. This heterojunction device produced a high Ion/Ioff ratio over 10,6 responsivity of 224 mA/W, specific detectivity of 1.5 × 1012 Jones, high polarization sensitivity, and broadband response up to 3043 nm. Furthermore, a 4 × 4 device array of WS2/Si heterojunction device is demonstrated with high stability and reproducibility. These results suggest that the WS2...

Photovoltaic Action With Broadband Photoresponsivity in Germanium-MoS2Ultrathin Heterojunction

The heterostructures fabricated with a combination of 2-D materials and conventional semiconductors are of great interest owing to their unique optoelectronic properties. Here, we demonstrate the fabrication of a germanium (Ge)/MoS2 heterostructure and observation of a photovoltaic action with broadband photoresponsivity. A thin interface was formed in-between the thermally evaporated Ge and chemical vapor deposited MoS2 layers, considering the atomically smooth surface of MoS2. The current density-voltage ( ${J}$ – ${V}$ ) measurement showed a diode like characteristic and photoresponsivity under light illumination. The Ge/MoS2 heterojunction showed an open circuit voltage ( ${V}_{\text {oc}}$ ) of 0.185 V and short circuit current density ( ${J}_{\text {sc}}$ ) of 0.028 mA/cm2 under illumination of light (wavelength 350–1100 nm). The transient photoresponse characteristics of the Ge-MoS2 heterojunction device showed significant photoresponsivity for ultraviolet, visible, and near-infrared light at different bias voltages. The interfacial charge transfer at the Ge-MoS2 heterojunction is the critical aspect to create an effective build in field for the broadband photoresponsive device. The demonstrated ultrathin heterojunction of Ge and MoS2 layers can be significant for developing self-powered broadband photodetectors.

Polarized Ferroelectric Field-Enhanced Self-Powered Perovskite Photodetector

The hybrid organic–inorganic perovskites have been considered as promising candidates for high-performance photodetectors. However, how to fabricate self-powered broadband perovskite photodetectors with tunable photoresponse is still challenging. Herein, we design, for the first time, a ferroelectric semiconductor SrTiO3 (STO) and perovskite film hybrid structure based photodetector. After applying appropriate poled bias, the hybrid photodetector exhibits higher responsivity and faster response speed as compared to an unpoled device and a device without an STO ferroelectric interlayer. By optimizing the STO interlayer density, the positively poled photocurrent and response speed are enhanced to 0.956 mA and 0.1 s at zero bias, respectively. The corresponding responsivity is as high as 0.73A/W at a wavelength of 550 nm, which is much higher than that of the device without an STO interlayer. The improved performance is attributed to the fact that positively polarized STO layers can provide a built-in potent...

Novel perovskite/TiO2/Si trilayer heterojunctions for high-performance self-powered ultraviolet-visible-near infrared (UV-Vis-NIR) photodetectors

Methylammonium lead halide perovskites have been reported to be promising candidates for high-performance photodetectors. However, self-powered broadband ultraviolet-visible-near infrared (UV-Vis-NIR) photodetection with high responsivity is difficult to achieve in these materials. Here, we demonstrate, for the first time, a novel trilayer hybrid photodetector made by combining an n-type Si wafer, TiO2 interlayer and perovskite film. By precisely controlling the thickness of the TiO2 layer, enhanced separation and reduced recombination of carriers at the Si–perovskite interface are obtained. As a result, perovskite film, when combined with a low-bandgap Si, extends the wavelength range of photo response to 1,150 nm, along with improved on/off ratio, responsivity, and specific detectivity, when compared to pristine perovskite. Results obtained in this work are comparable or even better than those reported for perovskite-based UV-Vis-NIR photodetectors. In particular, the hybrid photodetectors can operate in a self-powered mode. The mechanism of enhancement has been explored and it is found that the increased separation and reduced recombination of photogenerated carriers at the junction interface leads to the improved performance.