Photoelectric Energy Conversion Research Articles

Highly Efficient Photon Energy Conversion and Ultrasensitive Self-Powered Photodetection via a Monolithic p-3C-SiC Nanothin Film on p-Si/n-Si Double Junction.

The pursuit of increased efficiency of photoelectric energy conversion through optimized semiconductor structures remains highly competitive, with current results yet to align with broad expectations. In this study, we discover a significant enhancement in photocurrent performance of a p-3C-SiC nanothin film on p-Si/n-Si double junction (DJ) heterostructure that integrates p-3C-SiC/p-Si heterojunction and p-Si/n-Si homojunction. The vertical photocurrent (VPC) and vertical photoresponsivity exhibit a substantial enhancement in the DJ heterostructure, surpassing by a maximum of 43-fold compared to the p-3C-SiC/n-Si single junction (SJ) counterpart. The p-3C-SiC layer and n-Si substrate of the two heterostructures have similar material and geometrical properties. More importantly, the fabrication costs for the DJ and SJ heterostructure devices are comparable. Our results demonstrate a significant potential for using DJ devices in energy harvesters, micro/nano electromechanical systems, and sensing applications. This research may also lead to the creation of advanced optoelectronic devices using DJ structures, where employing various semiconductor materials to achieve exceptional performance through the application of the concept and theoretical model described in this work.

Giant photoelectric energy conversion via a 3C-SiC Nano-Thin film double heterojunction

Enhancing the energy conversion efficiency is utmost important in renewable energy and self-powered optoelectronic sensing applications. In this study, we propose the concept of a p-3C-SiC nano-thin film/p-Si/n-Si double junction (DJ) structure, which exhibits a massive photoelectric energy conversion efficiency and ultra-high sensitivity of optoelectronic sensors. The optoelectronic characteristics of this DJ heterostructure are compared to those of a p-3C-SiC/n-Si single-junction (SJ) heterostructure, which shares similarities in all technical and material parameters, except for the inclusion of the middle p-Si layer in the DJ structure. The experimental results reveal that the lateral photocurrent, sensitivity, theoretical power and maximum power of the DJ structure are more than 100 times (i.e. over 10,000%) greater than those of the SJ structure. We then demonstrated these excellent features of DJ heterostructure through developing of a self-powered position sensitive sensor, which showed an ultrahigh sensitivity. The enormous enhancement in the performance has been elucidated through the efficient photogeneration of charge carriers, electron-hole pair splitting, and the improved charge carrier transport mechanisms in the double heterojunction. This research represents a notable breakthrough in ultra-sensitive optoelectronic sensors and photoenergy conversion, since the proposed concept and theoretical model can be extended to multiple junctions of various semiconductor materials.

Photon-STM Study of Photoelectric Energy Conversion in a Single Molecule

Photon-STM Study of Photoelectric Energy Conversion in a Single Molecule

Strong room temperature exciton photoluminescence in electrochemically deposited Cu2O films

Strong room temperature exciton photoluminescence (PL) has been observed in copper (I) oxide films electrochemically deposited in a tartrate electrolyte. The PL intensity of these films is two orders of magnitude higher than that of films deposited from the classical lactate electrolyte. X-ray diffraction (XRD) and Raman spectroscopy analyses demonstrate that the films prepared using tartrate electrolyte are characterized by higher grain size, which reduces a non-radiative recombination of charge carriers. Better optical quality of the Cu2O films prepared using tartrate electrolyte is explained taking into account stronger tartrate-copper complexes, which results in lower density of grain boundaries in such films. Moreover, higher buffering capacity of the tartrate complex provides stability of pH value in the diffusion layer of the near-electrode space preventing defect formation. Our study demonstrates the promise of using Cu2O films deposited from tartrate solution for solar energy applications like photoelectric energy conversion, hydrogen production, and photocatalysis.

Energy harvesting feasibility from photovoltaic/thermal (PV/T) hybrid system with [formula omitted]-glycerol nanofluid optical filter

In this interdisciplinary experimental study a new nanofluid-based optical filter (NFOF) was designed and tested for a photovoltaic/thermal (PV/T) hybrid system. To this end, Ag/ Cr2O3 nanoparticles (NPs) were synthesized with 5% concentration of Ag, then the obtained Ag/Cr2O3 NPs were suspended in glycerol (C3H8O3). The prepared nanofluid optical filter is outstanding and novel from some aspects: (i) the simple synthesis method of Ag/Cr2O3 NPs, (ii) bears desirable transmittance, (iii) high stability of nanoparticles in base fluid, (iv) low-cost production process, (v) acceptable overall energetic and exergetic efficiency. The intense solar irradiance occurs in the visible spectrum range where most solar systems are designed based on this range. Moreover, the highest spectral response of the silicon type solar cells can be achieved in wavelengths between 650 nm and 1075 nm (ideal window). Therefore, the prepared NFOF filters was designed to have maximum transmittance in wavelengths between 650 nm and 1075 nm for efficient photo-electrical conversion. Accordingly, they should have high absorbance in the wavelengths out of the said region (especially visible spectrum) for optimum photo-thermal conversion. The incident of spectra out of ideal window not only doesn't have any contribution to PV cell electricity generation, but also increases cell temperature which subsequently reduces its efficiency and longevity. For this purpose, NFOF was used as a selective thermal absorber that protects PV cell against unrequired spectra. Three different concentrations of Ag/Cr2O3 NPs were suspended in glycerol (10 ppm, 40 ppm, and 80 ppm). The performance of the hybrid PV/T system was checked by photothermal/electrical conversion efficiency, merit function, and overall exergy efficiency. The maximum photothermal energy conversion efficiency is 31.55% which is obtained by Ag/Cr2O3-glycerol (80 ppm) NFOF. Also, the highest value of photoelectric energy conversion is 13.25% which is obtained when there is no filter. Moreover, the Ag/Cr2O3-glycerol (40 ppm) NFOF caused the highest amount of overall energy efficiency (41%) and merit function (1.558). When E(λ)≠0, the highest and lowest overall exergy efficiency during 30 min testing was obtained by glycerol and Ag/Cr2O3-glycerol (80 ppm), while this is completely inverse when E(λ) = 0.

Centimeter-scale perovskite SrTaO2N single crystals with enhanced photoelectrochemical performance

Large-scale single crystals have potential applications in many fields, such as in ferroelectric and photoelectric energy conversion devices. Perovskite oxynitrides have also attracted attention in photoelectrochemical water splitting systems because of their high theoretical solar-to-hydrogen efficiencies. Nevertheless, the synthesis of perovskite oxynitride single crystals requires the coupling of cation exchange and ammonization processes, which is exceptionally challenging. The present study demonstrates an inorganic vapor method that provides, for the first time ever, high-quality epitaxial perovskite SrTaO2N single crystals on the centimeter scale. Assessments using Raman spectroscopy, crystal structure analysis and density functional theory determined that the conversion mechanism followed a topotactic transition mode. Compared with conventional SrTaO2N particle-assembled films, the SrTaO2N single crystals made in this work were free of interparticle interfaces and grain boundaries, which exhibited extremely high performance during photoelectrochemical water oxidation. In particular, these SrTaO2N single crystals showed the highest photocurrent density at 0.6 V vs. RHE (1.20 mA cm−2) and the highest photocurrent filling factor (47.6%) reported to date, together with a low onset potential (0.35 V vs. RHE). This onset potential was 200 mV less than that of the reported in situ SrTaO2N film, and the photocurrent fill factor was improved by 2 to 3 times.

High-speed magnetolevitatve land transport with power supply by distributed photoelectric energy system with perspective energy storage

Among the various types of high-speed land transport a magnetic levitation transport (magnetoplanes) is recognized as the most promising, so research related to the improvement of this type of transport is relevant. The work is devoted to the integra-tion of three promising research technologies: magnetolevitative transport, photoelec-tric energy conversion and phase-metric radionavigation. It is this integration, i.e. the essential interpenetration of these three subsystems, results in an overall synergistic ef-fect. Achieving the goals of sustainable development of the national economic complex within the framework of traditional transport and energy technologies is problematic, as energy consumption of transport systems exceeds one third of energy consumption, and the fastest mode of transport – an air transport is one of the leading air pollutants. Therefore, the purpose of this work is to substantiate a promising way to solve this problem by combining in a single system of renewable energy technologies and magne-tolevitative transport. The methods of system analysis and decomposition, statistical analysis of solar insolation, radiophysical experiment, computer modeling of photovol-taic energy converters, algorithmization of current control processes and forecasting the energy storage devices state are involved. The result of the research is the development of physical and technical bases for the improvement of magnetolevitative transport. Conclusion: by combining in a single system of renewable energy technologies and mag-netic levitation transport it is possible to create a system of all-weather guaranteed power supply based on solar energy and a reliable precision high-speed control system in real time.

First principles study on the structures and properties of SnO–ZnO alloys under high pressure

SnxZn1-xO alloys are potential candidates to be widely used in photoelectric solar energy conversion, gas sensors and other fields. However, their crystal structures and physical properties have not been systematically studied, which hinders their in-depth investigation. Herein, we used USPEX software package to search for the crystal structures of SnxZn1-xO alloys in the pressure range of 0–60 GPa. A new ground state structure of SnZnO2 (Cmcm) and several other metastable structures of SnxZn1-xO were predicted. Our studies showed that pressure can be an effective method to promote the formation of stable SnO–ZnO alloys. The dynamic and mechanical stabilities of the predicted crystal structures were established by calculating the phonon spectra and elastic properties of the crystals. Finally, the electronic structures and optical properties of SnxZn1-xO system were investigated using the first-principles calculations. The optical absorption coefficient of SnZnO2 as a function of pressure was calculated, and the results showed that the absorption peaks move to higher energy as the pressure increases.

Two-dimensional transition metal chalcogenide nanomaterials for cancer diagnosis and treatment

For more than a decade, the exfoliation of graphene and other layered materials has led to a tremendous amount of research in two-dimensional (2D) materials, among which 2D transition metal chalcogenides (TMCs) nanomaterials have attracted much attention in a wide range of applications including photoelectric devices, lithium-ion batteries, catalysis, and energy conversion and storage owing to their unique photoelectric physical properties. With such large specific surface area, strong near-infrared (NIR) absorption and abundant chemical element composition, 2D TMCs nanomaterials have become good candidates in biomedical imaging and cancer treatment. This review systematically summarizes recent progress on 2D TMCs nanomaterials, which includes their synthesis methods and applications in cancer treatment. At the end of this review, we also highlight the future prospects and challenges of 2D TMCs nanomaterials. It is expected that this work can provide the readers with a detailed overview of the synthesis of 2D TMCs and inspire more novel functional biomaterials based on 2D TMCs for cancer treatment in the future. 2D transition metal chalcogenides (TMCs) have received growing attention in biomedical imaging and cancer treatment because of their large specific surface area, strong near-infrared (NIR) absorption and abundant chemical element composition.

Design strategies of ZnO heterojunction arrays towards effective photovoltaic applications

AbstractZnO nanorods (NRs) heterojunction arrays have been widely used in photovoltaic cells owing to the outstanding photoelectrical chracteristics, high stability and low cost. The NRs arrays structure can integrate multiple functional components, so that it can exhibit more excellent physical and chemical properties that even independent components do not possess. The design of heterojunction nanostructures can effectively solve the problems of light absorption and carrier transport. First, the synthesis methods of ZnO NRs and their heterojunction arrays were systematically introduced, including traditional chemical vapor deposition (CVD), electrodeposition, hydrothermal method, and so on, the different structures and properties of ZnO NRs heterojunctions were analyzed. Then, the selected materials could be further processed and assembled into NRs array heterojunction with integrated functions were discussed. The strategies of maximizing energy conversion performance (structure optimization, heterojunction, surface plasmon resonance, and doping) were emphatically summarized. In addition, the research progress of ZnO NRs and their heterojunctions in photoelectric energy conversion system were summarized, and the application potential of combining nanostructure design with solar cells was summarized. Finally, the challenges and future development prospects of ZnO NRs and their heterojunction arrays in photovoltaic conversion were pointed out.

Thermodynamic bounds of work and efficiency in near-field thermoradiative systems

Thermoradiative (TR) device combined with near-field radiation has been recently proposed to enhance noncontact direct photoelectric energy conversion. Based on the fluctuation-dissipation theorem, we evaluate the maximum work flux and the fundamental efficiency limit of the near-field TR systems by analyzing the radiative heat flux and the entropy flux. For a near-field TR system, when the ZrC absorber is placed close to the TR cell with a vacuum gap down to 100 nm, photon tunneling through evanescent waves can significantly enhance the maximum work flux without a compromise in efficiency limit. Furthermore, the decrease in the temperature of the heat source would greatly weaken the performance of the TR system. We also would like to emphasize that the hyperbolic metamaterial (HMM) and Lorentz absorbers can remarkably improve the performance of the TR system as compared to the ZrC reference. In this paper, based on the proposed method for determining the thermodynamic bounds of work and efficiency, we establish a target for the performance of the near-field TR system. In addition, the fundamental understandings and insights obtained in this study will facilitate the design and application of the near-field TR system.

Epitaxial halide perovskite-based materials for photoelectric energy conversion

A review on epitaxial perovskite structures from material combinations and structural motifs to photoelectric energy conversion applications.

Stimulation of Photoactive Absorption of Sunlight in Thin Layers of Silicon Structures by Metal Nanoparticles

This study is devoted to analysis by the method of modeling photoelectric processes of charge transfer in thin silicon structures with a p–n junction containing nanoparticles of various metals, their sizes, and volume distribution.The absorption and current–voltage (I–V) characteristics of thin-film silicon solar cells, which contain the metal nanoparticles localized on the surface dielectric antireflecting coating, in the emitter and base with high and low doping degree, and on the interfaces of these layers, are defined. As a basic method for research, the Sentaurus TCAD is chosen, which includes the Structure Device Editor, Sentaurus Device, Sentaurus Visual, and Sentaurus Workbench packages with wide capabilities for modelling silicon solar cells with a flat p–n junction. The absorption and I–V characteristics of photoelectric converters, containing metal nanoparticles in various thin layers of the structure, are determined by analyzing the computational results and discussing the physical nature of observable processes. The recommendations are offered for creating thin-film silicon plasmonic p–n junction solar cells with optimized sizes of metal nanoparticles, their distribution, and, hence, with improved efficiency of photoelectric conversion of energy. The expediency of creation of ultraviolet radiation detectors on the basis of thin-film silicon structures with metal nanoparticles is shown. The absorption and I–V characteristics of photoelectric converters, containing metal nanoparticles in thin layers of the dielectric coating, emitter, and base with high and low doping degrees and also on interfaces of these layers are compared. The most effective absorption of the solar spectrum in the region of the emitter up to the metallurgical border of the p–n junction and the best efficiency of photoelectric energy conversion of silicon solar cells are revealed. The optimum sizes of metals nanoparticles, regularities of their distribution, and depths of occurrence of the p–n junction for thin layers of crystalline silicon are defined. The recommendations for creation of third-generation thin-film silicon plasmonic solar cells and high-sensitivity photovoltaic detectors of ultra-violet radiation are developed.

Giant photothermoelectric effect in silicon nanoribbon photodetectors

The photothermoelectric (PTE) effect enables efficient harvesting of the energy of photogenerated hot carriers and is a promising choice for high-efficiency photoelectric energy conversion and photodetection. Recently, the PTE effect was reported in low-dimensional nanomaterials, suggesting the possibility of optimizing their energy conversion efficiency. Unfortunately, the PTE effect becomes extremely inefficient in low-dimensional nanomaterials, owing to intrinsic disadvantages, such as low optical absorption and immature fabrication methods. In this study, a giant PTE effect was observed in lightly doped p-type silicon nanoribbons caused by photogenerated hot carriers. The open-circuit photovoltage responsivity of the device was 3-4 orders of magnitude higher than those of previously reported PTE devices. The measured photovoltage responses fit very well with the proposed photothermoelectric multiphysics models. This research proposes an application of the PTE effect and a possible method for utilizing hot carriers in semiconductors to significantly improve their photoelectric conversion efficiency.

Electric hybrid airship with unlimited flight time

This paper examines the possibility of using photoelectric energy conversion during creation of electric unmanned aerial vehicles of a hybrid type. These vehicles should operate at altitudes up to 22,000 m and have an unregulated flight time. The problems arising during creation of such devices are their instability and poor controllability. Also they possess a number of disadvantages typical for airships: large size and, as a consequence, high windage and dependence on weather conditions; low maneuverability and, as a consequence, the difficulty of landing. These negative aspects of all circular wings resulted in complete rejection of their development. However, the considered disadvantages show the feasibility of creating hybrid aircraft. Particular attention in this paper is given to disk-shaped vehicles. They have less windage, do not need to turn around when changing the direction of flight. The presence of solar panels in combination with modern control and navigation systems make it possible to create new unmanned aerial vehicles with unlimited flight time. The aircraft dimensions are calculated as a function of the lifted mass and other parameters. Recommendations on possible operation parameters of hybrid airship are given.

Reaction Spinning Titanium Dioxide Particle-Coated Carbon Fiber for Photoelectric Energy Conversion

In this paper, a titanium dioxide particle coated carbon fiber was prepared by reaction spinning. Polyacrylonitrile (PAN) was used as the precursor to generate a continuous carbon nanofiber. A solution containing 10% wt PAN polymer dissolved in dimethylformamide (DMF) was made as the core fluid. The sheath fluid contains 10% titanium (IV) isopropoxide, 85% ethanol, and 5% acetic acid. The two solutions were co-spun onto an aluminium plate covered with a layer of soft tissue paper. A titanium hydroxide layer formed at the surface of the PAN fiber through the hydrolysis of titanium isopropoxide due to the moisture absorption in the co-spinning process. The reaction spun fiber was converted to a partially carbonized nanofiber by the heat treatment in air at 250 °C for two hours, then in hydrogen at 500 °C for two hours. During the early stage of the heat treatment, the titanium hydroxide decomposed and produced titanium dioxide nanoparticles at the surface of the carbon fiber. The structure and composition of the carbonized fiber were studied by scanning electron microscopy (SEM). The photosensitivity of the particle-containing fiber was characterized by measuring the open circuit voltage under visible light excitation. The photoelectric energy conversion behavior of the fiber was confirmed by open circuit potential measurement. The potential applications of the composite fiber for photovoltaics and photonic sensing were discussed.

Artificial light-driven ion pump for photoelectric energy conversion

Biological light-driven ion pumps move ions against a concentration gradient to create a membrane potential, thus converting sunlight energy directly into an osmotic potential. Here, we describe an artificial light-driven ion pump system in which a carbon nitride nanotube membrane can drive ions thermodynamically uphill against an up to 5000-fold concentration gradient by illumination. The separation of electrons and holes in the membrane under illumination results in a transmembrane potential which is thought to be the foundation for the pumping phenomenon. When used for harvesting solar energy, a sustained open circuit voltage of 550 mV and a current density of 2.4 μA/cm2 can reliably be generated, which can be further scaled up through series and parallel circuits of multiple membranes. The ion transport based photovoltaic system proposed here offers a roadmap for the development of devices by using simple, cheap, and stable polymeric carbon nitride.

Polyion Charge Ratio Determines Transition between Bright and Dark Excitons in Donor/Acceptor-Conjugated Polyelectrolyte Complexes

There is substantial urgency to create artificial light-harvesting systems that are relatively inexpensive and capable of absorbing a significant fraction of the solar spectrum. Molecular materials possess a number of attractive characteristics for this purpose, such as their light weight, spectral tunability, and the potential to use self-assembly to form large structures capable of executing multiple photophysical processes required for photoelectric energy conversion. In this work, we demonstrate that ionically assembled complexes composed of oppositely charged conjugated polyelectrolytes (CPEs) that function as excitonic donor/acceptor pairs possess 10 significant potential as artificial energy transfer antennae. We find that, upon complexation in water, excitation energy is transferred from the donor to the acceptor CPE in less than 250 fs—a timescale that is competitive with natural light-harvesting antennae. We further find that the state of CPE chain extension and thus spatial delocalization of th...

An all-inorganic perovskite solar capacitor for efficient and stable spontaneous photocharging

Integrated energy “harvesting-storage” devices, especially photocharging devices that can simultaneously achieve the functions of photoelectric energy conversion and electrochemical energy storage, have attracted enormous attention to serve as sustainable and portable distributed power sources. However, the performance of photocharging devices is usually restricted by small voltage plateau and low energy conversion efficiency. Herein, we report a novel “solar capacitor” realized by combining a CsPbBr3 based all-inorganic perovskite solar cell (PSC) and an all-inorganic silica-gel-electrolyte based supercapacitor into a single device. Benefited from the synergy of these two components, the solar capacitor can simultaneously realize the functions of solar power harvesting and electrochemical energy storage without the aid of galvanostatic charging. This device has the merits of compact structure, very fast photocharging rate and high stability, exhibiting a record voltage plateau of 1.2 V and a remarkable overall “photo-electrochemical-electricity” energy conversion efficiency of 5.1%. This work provides new insights for designing novel energy conversion-storage integrated systems.

Phototriggered Selective Actuation and Self‐Oscillating in Dual‐Phase Liquid Crystal Photonic Actuators

AbstractAmong different kinds of photoactuators available, those based on liquid‐crystal polymer networks (LCNs) are gathering a great deal of attention due to their fast response and versatility of structural design. However, only a few reports have focused on the phototriggered LCN actuators for complex actuation and multifunction properties. Here, a phototriggered LCN‐based photonic actuator with quasi‐bilayer structure that exhibits fast and reversible shape changes is created by infiltrating a LCN precursor–graphene oxide mixture into a silica opal template, ultraviolet photopolymerization, and removing the template. Particularly, the phototriggered selective actuation behavior is achieved in dual‐phase LCN‐based photonic actuators with macroscopically alternating nematic (N) and isotropic (I) phase, which enables versatile actuation modes and allows multiple shape changes. In addition, a two‐segmented, dual‐phase LCN‐based photonic actuator exhibits self‐oscillating motion when a responsive N‐phase region as localized active point is irradiated, which arises from the self‐shadowing of the passive I‐phase region. To demonstrate the potential application of this self‐oscillating motion behavior, a photoelectric energy conversion device that is capable of converting light energy to electric energy is constructed.