Photoelectric Conversion System Research Articles

Axial InN/InGaN Nanorod Array Heterojunction Photodetector with Ultrafast Speed

AbstractDue to wavelength‐selective characteristics, the InGaN‐based photodetectors show bright prospects in visible light communication and fast imaging system. However, the application of InGaN photodetectors with simple structures is limited in the above field owing to the slow response speed. Herein, an ultrafast photodetector based on axial InN/InGaN nanorod array (NRA) heterojunction is prepared through a self‐catalytic high (930 °C) and low (400 °C) temperature two‐step growth method by molecular beam epitaxy (MBE). The performance of photodetectors is analyzed by semiconductor device analyzer, wavelength response system (consists with a xenon lamp and monochromator), and time response system (combined by an optical chopper, a laser, and a digital oscilloscope). The photodetectors present a fast response speed with a rise/full time of 18.2/24.7 µs. Further analyses reveal a responsivity of 9.27 A W−1 and a specific detectivity of 3.54 × 1010 Jones under −1 V bias. As a result, the axial NRA heterojunction photodetectors exhibit great potential for application in ultrafast photoelectric conversion systems and provide valuable guidance for realizing ultrafast photodetectors.

Two-Layer Ring Truss-Based Space Solar Power Station

A space solar power station (SSPS) has become a huge potential candidate to provide abundant and clean electrical energy for terrestrial users by collecting and converting solar power in space. In this paper, an innovative two-layer ring truss-based SSPS is proposed. It consists of the top layer concentrator-based spherical one-time reflection region, the bottom layer space radiator using symmetric or asymmetric cable networks, a ring truss for a supporting structure, a photoelectric conversion system, and transmitting antennas. The construction strategies including the triangular facets modularity of top layer concentrator, area requirement of bottom layer space radiator, two-segment optimization design of generatrix of photoelectric conversion system, and aperture derivation of transmitting antenna are carried out. Then, the performance analysis mainly including the modularization theory error calculation, energy collection and distribution, and thermal characteristics in orbit of this proposed SSPS is presented. Finally, the system parameters are estimated and summarized for a better sense of the proposed SSPS. The results indicate that 100% energy collection can be achieved for an ideal concentrator, and 80% with a modular division layer of 6 and tracking error of no more than 2°. The results demonstrate the feasibility of the proposed SSPS concept and can provide a reference for future space energy harvesting and space exploration projects.

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.

Accurate Analysis of Anisotropic Carrier Mobility and Structure-property Relationships in Organic BOXD Crystalline Materials.

Charge mobility is an essential factor of organic crystalline materials. Although many investigators have made important progress, the exact relationship between the crystal structure and carrier mobility remains to be clarified. Fortunately, a series of bis-1,3,4-oxadiazole derivatives have been successfully prepared and reported. They have similar main molecular fragments but different crystal packing modes, which provide an ideal research objective for studying the effect of molecular packing on charge mobility in organic photoelectric conversion systems. In this work, the charge mobilities of these molecules are systematically evaluated from the perspective of first-principles calculation, and the effect of a molecular overlap on orbital overlap integral and final charge carrier mobility is fully discussed. It can be seen that the small intermolecular distance (less than 6 Å) is the decisive factor to achieve high electron mobility in π stacking, and better mobility can be obtained by increasing the hole migration distance appropriately. A larger dihedral angle of anisotropy is an important point limiting the charge mobility in the herringbone arrangement. It is hoped that the correlation results between the crystal structure and mobility can assist the experimental study and provide an effective way to improve the photoelectric conversion efficiency of the organic semiconductor devices and multiple basis for multiscale material system characterization and material information.

Bio-organic-inorganic Hybrid Soft Materials: Photoelectric Conversion Systems Based on Photosystem I and II with Molecular Wires

This review discusses methods for increasing the efficiency of photoelectric conversion systems using photosystem I (PSI) and photosystem II (PSII) isolated from thermophilic cyanobacteria. The str...

A sensitive label-free photoelectrochemical aptasensor based on a novel PTB7-Th/H2O2 system with unexpected photoelectric performance for C-reactive protein analysis

Herein, a sensitive label-free photoelectrochemical (PEC) aptasensor was constructed for C-reactive protein (CRP) analysis based on a novel and efficient poly{4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)carbonyl] thieno[3,4-b]-thiophene-4,6-diyl} (PTB7-Th)/H2O2 system with unexpected photoelectric performance. The proposed PTB7-Th/H2O2 system without any sensitizer could surmount defect of the poor photoelectric conversion efficiency of PTB7-Th, leading to the unexpected 10-fold photocurrent enhancement compared to the common PTB7-Th/PBS system. The strong enhancement effect might originate from the special function of hydrogen peroxide (H2O2) towards PTB7-Th. On the one hand, H2O2 as electron acceptor could continuously capture photogenerated electrons located at acceptor part of PTB7-Th, which would visibly improve the charge separation efficiency of PTB7-Th and the electron-receiving property of electrolyte solution, thus leading to the obviously enhanced photoelectric conversion efficiency (PCE). More importantly, H2O2 as oxidant could oxidize PTB7-Th to obtain oxidation product of PTB7-Th (OPP) with carbonyl group and carboxyl group, and the electron cloud density in donor part of the OPP was higher than that of PTB7-Th, therefrom producing the stronger electron-donating property and higher photoelectrochemical (PEC) reaction efficiency. As a proof of concept, the proposed PTB7-Th/H2O2 system was successfully applied in the construction of a label-free PEC aptasensor for sensitive analysis of CRP, which performed a wide detection range from 1 pM to 1000 nM with a low detection limit of 0.33 pM. This study demonstrated a novel approach to the rational design of photoelectric conversion system with high PEC performance and provided an inspired tack for the construction of high-efficiency photoelectric devices.

Light-Responsive Proton Conductor: Record High Gain of Proton Conductivity Achieved by Photoinduced Electron-Transfer Strategy

Light-Responsive Proton Conductor: Record High Gain of Proton Conductivity Achieved by Photoinduced Electron-Transfer Strategy

A Visible-Light-Regulated Chloride Transport Channel Inspired by Rhodopsin.

Inspired by the light-regulating capabilities of naturally occurring rhodopsin, we have constructed a visible-light-regulated Cl- -transport membrane channel based on a supramolecular host-guest interaction. A natural retinal chromophore, capable of a visible-light response, is used as the guest and grafted into the artificial channel. Upon introduction of an ethyl-urea-derived pillar[6]arene (Urea-P6) host, threading or de-threading of the retinal and selective bonding of Cl- can be utilized to regulate ion transport. Based on the visible-light responsiveness of the host-guest interaction, Cl- transport can be regulated by visible light between ON and OFF states. Visible-light-regulated Cl- transport as a chemical model permits to understand comparable biological ion-selective transport behaviors. Furthermore, this result also supplies a smart visible-light-responsive Cl- transporter, which may have applications in natural photoelectric conversion and photo-controlled delivery systems.

Plasmonic Hydrogen Evolution at p-Type Semiconductor Electorode

The efficient control of the visible light driven hydrogen evolution reaction can be recognized as the one of the promising challenge for the sustainable society. It can be said that the wide-band semiconductor electrode is the promising material for the photo-energy conversion system. However, various semiconductor electrodes have the limitation to the ultraviolet region because of their wide band gap energy. Recently, plasmoic photoelectric conversion system, which is the combination of the plasmon active metal nano-structures with the semiconductor substrate, has been received much attention because the system shows the visible light response characters beyond the limitation of the limitation. In this system, the electrons excited in the metal structures injected into the conduction band of the n-type semiconductor and the remained holes are consumed through the oxidation reaction. Up to now, various plasmon-induced chemical reactions, even the water splitting, have been proposed. As our previous study, we have not only visualized the reaction active sites but also determined the reaction active species through the polymerization reactions of the conductive polymer. Although well-established systems have been reported, the direct control of the reduction reaction at the metal-semiconductor interface by the excited electrons has not been well examined. This is because the almost plasmonic photoconversion systems consist of the n-type semiconductor electrode and applied the generated holes to the reactions. In this study, we have tried to establish the plasmon-induced hydrogen evolution system by the introduction of the plasmon-active metal nano-structures into the p-type semiconductor substrate. By supporting the plasmonic structures, we have confirmed the photo-current generation under the visible light illumination.[1] Through the photocurrent measurements and the incident photon to current conversion efficiency obtained under different pH conditions, we have confirmed the unique pH dependence. In addition to these, we have also investigated the isotopic effect on the hydrogen evolution reaction to clarify the unique surface molecular process. Through the various photoelectrochemical measurements, we are sure that our plasmonic hydrogen evolution system could be one of the good candidate for future light energy conversion system. [1] D. Sato, H. Minamimoto, and K. Murakoshi, Chem. Lett., in press.

Photoelectric Conversion System Composed of Gene-Recombined Photosystem I and Platinum Nanoparticle Nanosheet.

Photosynthesis is one of the most vital processes in nature, which consists of two main photoreaction centers called photosystem I and photosystem II. The high quantum yield of photosystem I (PSI) makes it attractive for bioelectronic applications. However, the native PSI (N-PSI) loses its robust photochemical properties once fabricated into devices. This property degradation results from the difficulty in controlling the orientation of PSI. With the optimal orientation of PSI, photoexcited electrons can easily reach the electrode, yielding good photoelectric conversion efficiency. We developed a novel photoelectrode by integrating a newly designed gene-recombined PSI (G-PSI) with platinum nanoparticles (PtNPs) on substrates using a simple stacking method, which can control the orientation of PSI on the electrode. The target orientation of the attached G-PSI toward the substrate was confirmed by the absorption spectra of polarized light. An approximately 2-fold increase in the internal quantum yield (IQY) was observed for the G-PSI-attached electrode under 680 nm irradiation compared with that of the N-PSI-modified electrode. In addition, a 4-fold enhancement of the IQY was detected for cytochrome c (Cyt c) stacking on the G-PSI because of the electrostatic interaction, suggesting that Cyt c successfully secured the electron-transfer pathway.

Plasmonic Hydrogen Evolution Reactions Driven By Visible Light Illumination at p-Type Semiconductor Electrodes

The efficient control of the visible light driven hydrogen evolution reaction can be recognized as the one of the promising challenge for the sustainable society. It can be said that the wide-band semiconductor electrode is the good material for the photo-energy conversion system. However, various semiconductor electrodes have the limitation to the ultraviolet region because of their wide band gap energy. Recently, plasmoic photoelectric conversion system, which is the combination of the plasmon active metal nano-structures with the semiconductor electrodes, has been received much attention because the system shows the visible light response characters beyond its limitation. In this system, the electrons excited in the metal structures injected into the conduction band of the n-type semiconductor and the remained holes are consumed through the oxidation reaction. Up to now, various plasmon-induced chemical reactions, even the water splitting, have been proposed. As our previous study, we have not only visualized the reaction active sites but also determined the absolute electrochemical potential of the reaction active species through the polymerization reactions of the conductive polymer.1 Although well-established systems have been reported, the direct control of the reduction reaction at the metal-semiconductor interface by the excited electrons has not been well examined. This is because the almost plasmonic photoconversion systems consist of the n-type semiconductor electrode and applied the generated holes to the reactions. In this study, we have tried to establish the plasmon-induced hydrogen evolution system by the introduction of the plasmon-active metal nano-structures into the p-type semiconductor electrodes. By supporting the plasmonic structures, we have confirmed the photo-current generations under the visible light illumination. Through the photocurrent measurements and the incident photon to current conversion efficiency obtained under different pH conditions, we have confirmed the unique pH dependence. In addition to these, we have also investigated the isotopic effect on the hydrogen evolution reaction to clarify the unique surface molecular process.2 Through the various photoelectrochemical measurements, we are sure that our plasmonic hydrogen evolution system could be considered as one of the good candidate for future light energy conversion system.Reference 1. Minamimoto and K. Murakoshi et al., J. Phys. Chem. C., 120(29), 16051 (2016).2. Minamimoto, R. Osaka, and K. Murakoshi, Electrochimica Acta, 304(1), 87 (2019).

Reducing the Schottky Barrier by SnS2 Underlayer Modification to Enhance Photoelectric Performance: The Case of Ag2S/FTO.

The transfer and recombination of photoinduced charge carriers play the crucial roles in a photoelectric conversion system. In this work, the Ag2S/fluorine-doped tinoxide (FTO) was used as the platform to understand the photoinduced charge carrier transfer and recombination at the light absorber and electrode interface. SnS2 was evaporated onto the FTO surface to cooperate the Fermi level with Ag2S, which reduced the Schottky barrier at the Ag2S/FTO interface. Kelvin probe force microscopy measurements reveal that the Fermi level of FTO can be tuned from -4.93 to -4.75 eV by various SnS2 with different evaporation amounts. Transient surface photovoltage tests confirm that the recombination of the photogenerated charge carrier can be drastically suppressed. The photoelectric conversion efficiency of the resulting solar cell devices has been significantly improved.

Hydrogen Evolution Reaction Catalyzed By Plasmoinic Photo-Electrodes Under Visible Light Illumination

From the environmental point of view, the efficient control of the visible light driven hydrogen evolution reaction is one of the promising issue. For that, the semiconductor electrode can be regarded as the sufficient material but various semiconductor electrodes cannot be used for the visible light driven reactions due to their wide band gap energy. Recently, plasmoic photoelectric conversion system, which is the introduction of the plasmon active metal nano-structures onto the surface of the semiconductor substrate, has been received much attention due to its wide range photo response abilities. In this system, the electrons are excited and injected into the conduction band of the n-type semiconductor under visible light illuminations. Up to now, various plasmon-induced chemical reactions, even the water splitting, have been established. However, although well-established systems have been reported, the direct control of the reduction reaction at the metal-semiconductor interface using the excited electrons has not been well examined because the almost plasmonic photoconversion systems consist of the n-type semiconductor electrode and used the generated holes for the reactions. In this study, we have tried to establish the plasmon-induced hydrogen evolution system by using p-type semiconductor substrate and plasmon active nano-structures. By the fabrication of the plasmonic Ag dimer structures, we have observed the generation of the photo-current derived from the hydrogen evolution reactions under visible light illumination. Through the photocurrent measurements and the incident photon to current conversion efficiency obtained under different pH conditions, we have confirmed the pH dependence of the photo current value and the photo response characters. In addition to these, as the very interesting point for the current study, we have found the very unique catalytic property for the plasmonic hydrogen evolution especially under specific pH condition. Through the various photoelectrochemical measurements including isotropic selectively, we are sure that our plasmonic hydrogen evolution system could be one of the good candidate for future light energy conversion system.

Multispectral Plasmon of Anisotropic Core-shell Gold Nanorods@SiO2: Dual-band Absorption Enhancement with Coupling Dye Molecules

Direct evidence of effects of surface plasmon resonance(SPR) of gold nanorods(GNRs) on dual-band light absorption enhancement with coupling dye molecules was reported by introducing gold nanorod@SiO2(GNR@SiO2) core-shell nanoparticles into a photoelectric conversion system. GNR with asymmetric shape had unusual anisotropic SPR[transversal surface plasmon resonance(TSPR) and longitudinal surface plasmon resonance(LSPR)]. The excel-lent SPR of GNR made it a promising candidate as enhancing light absorption material to increase power conversion efficiency(PCE). The PCE was improved nearly 17.2% upon incorporating GNRs, mostly due to the increase in Jsc, while Voc and FF were unchanged. The improvement was mostly contributed by the SPR of the GNRs with coupling of N719. And there was also a complementary to N719 in visible light range. Therefore, SPR is an effective tool in improving the photocurrent and consequently enhancement of PCE. The TSPR and LSPR effects of GNRs on light harvesting were reflected in the increased monochromatic incident photon-to-electron conversion efficiency(IPCE). We also utilized finite-difference time-domain(FDTD) to investigate the light coupling of GNRs with TiO2. Compare to the base anode, the IPCE of optimized electrode showed significant improvement and peaks broadening at 500–600 nm and 610–710 nm. We got an increase in overall conversion efficiency from 6.4% to 7.5%.

Research on Photoelectric Detection System Applying to UV-VIS Spectroscopy Water Quality Monitoring System

In order to solve the problem of low luminous flux and quantum efficiency of the photoelectric detection system of UV-Visible spectroscopy water quality monitoring, a photoelectric detection system with high flux, stray light and enhanced sensitivity to ultraviolet band has been developed. The study of simulation design is carried out by using ZEMAX optical analysis software. According to the theoretical calculation of water absorption characteristic band, concave grating is used as the light splitting element. Through reasonable optical design and compact structure layout, the stable operation in spectral range of 200 to 800nm is achieved. The simulation results show that the resolution of the photoelectric conversion system is better than 2nm, which meets the requirements of the water quality detection of UV-Visible spectrum.

Photofunctionality in Porphyrin‐Hybridized Bis(dipyrrinato)zinc(II) Complex Micro‐ and Nanosheets

AbstractNew bis(dipyrrinato)zinc(II) complex micro‐ and nanosheets containing zinc(II) porphyrin (N2) are synthesized. A liquid/liquid interface method between dipyrrin porphyrin ligand L2 and zinc acetate produces N2 with a large domain size. N2 can be layered quantitatively onto a flat substrate by a modified Langmuir–Schäfer method. N2 deposited on a SnO2 electrode functions as a photoanode for a photoelectric conversion system. The photoresponse of N2 covers the whole visible wavelength range (400–650 nm), with a maximum quantum efficiency of more than twice that of a bis(dipyrrinato)zinc(II) complex nanosheet without porphyrin.

Photofunctionality in Porphyrin-Hybridized Bis(dipyrrinato)zinc(II) Complex Micro- and Nanosheets.

New bis(dipyrrinato)zinc(II) complex micro- and nanosheets containing zinc(II) porphyrin (N2) are synthesized. A liquid/liquid interface method between dipyrrin porphyrin ligand L2 and zinc acetate produces N2 with a large domain size. N2 can be layered quantitatively onto a flat substrate by a modified Langmuir-Schäfer method. N2 deposited on a SnO2 electrode functions as a photoanode for a photoelectric conversion system. The photoresponse of N2 covers the whole visible wavelength range (400-650 nm), with a maximum quantum efficiency of more than twice that of a bis(dipyrrinato)zinc(II) complex nanosheet without porphyrin.

Efficient Photocurrent Enhancement from Porphyrin Molecules on Plasmonic Copper Arrays: Beneficial Utilization of Copper Nanoanntenae on Plasmonic Photoelectric Conversion Systems.

We demonstrated the usefulness of Cu light-harvesting plasmonic nanoantennae for the development of inexpensive and efficient artificial organic photoelectric conversion systems. The systems consisted of the stacked structures of layers of porphyrin as a dye molecule, oxidation-suppressing layers, and plasmonic Cu arrayed electrodes. To accurately evaluate the effect of Cu nanoantenna on the porphyrin photocurrent, the production of Cu2O by the spontaneous oxidation of the electrode surfaces, which can act as a photoexcited species under visible light irradiation, was effectively suppressed by inserting the ultrathin linking layers consisting of 16-mercaptohexadecanoic acid, titanium oxide, and poly(vinyl alcohol) between the electrode surface and porphyrin molecules. The reflection spectra in an aqueous environment of the arrayed electrodes, which were prepared by thermally depositing Cu on two-dimensional colloidal crystals of silica with diameters of 160, 260, and 330 nm, showed clear reflection dips at 596, 703, and 762 nm, respectively, which are attributed to the excitation of localized surface plasmon resonance (LSPR). While the first dip lies within the wavelengths where the imaginary part of the Cu dielectric function is moderately large, the latter two dips lie within a region of a quite small imaginary part. Consequently, the LSPR excited at the red region provided a particularly large enhancement of porphyrin photocurrent at the Q-band (ca. 59-fold), compared to that on a Cu planar electrode. These results strongly suggest that the plasmonic Cu nanoantennae contribute to the substantial improvement of photoelectric conversion efficiency at the wavelengths, where the imaginary part of the dielectric function is small.

Enhancement of Porphyrin Photocurrent Based on Plasmonic Cu Light-Harvesting Nanoantenna

Introduction Plasmonic metal-nanostructured electrodes have been used for the development of high-performance organic photoelectric conversion systems because they can act as superior light-harvesting nanoantennae. Many previous reports have demonstrated that this optical phenomenon led to a substantial enhancement of the photocurrent from porphyrin dyes. The enhancement mechanism has been suggested to be a significant enhancement of the photoexcitation efficiency of the dyes, which were located within the strong local electromagnetic fields generated via a localized surface plasmon resonance (LSPR) of the metal nanostructures. However, all of the plasmonic electrodes reported so far are composed of expensive metallic species (Au and Ag). We believe that the components of the plasmonic electrodes should be inexpensive and that the enhancement of photoelectric conversion efficiency using “inexpensive plasmonic nano-antenna materials” is an important goal because one of the main advantages of the organic photoelectric conversion systems is low cost due to the use of organic dyes. In this study, we fabricated photoelectric conversion systems consisting of hybrids of porphyrin molecules as a dye and a plasmonic Cu arrayed electrode because the Cu material is significantly cheaper than the traditional plasmonic materials. Experimental section The arrayed electrodes were fabricated by thermally-depositing Cu onto the two-dimensional silica colloidal crystals consisting of silica particles with 160, 260, and 330 nm in diameters.1 Effective suppression of the spontaneous oxidation of the Cu electrodes by protecting with the ultrathin layers consisting of mercaptohexadecanoic acid and the ultrathin sol-gel layers of Ti(O) and polyvinyl alcohol has allowed us to accurately evaluate the Cu nanoantenna effect on the porphyrin photocurrent. The porphyrin monolayers were immobilized onto the surface of the colloidal crystals. Results and Discussions The Cu LSPR could be tuned from visible to near-infrared wavelengths by controlling the underlying silica diameter. The resultant LSPR above 600 nm was efficiently excited where the interband transition is comparatively low. Also, the molecular ultrathin films, which covered the Cu surfaces, effectively suppress the spontaneous oxidation in the air and electrolyte aqueous solution. Photocurrent measurements for porphyrin-immobilized Cu arrayed electrodes (working electrode) were carried out in an aqueous 0.1 M NaClO4 solution containing 5 mM methyl viologen dichloride as an electron acceptor, using a three electrode photoelectrochemical cell. Ag|AgCl (sat. KCl aq.) and platinum wire were used as the reference and counter electrodes, respectively. Photocurrents generated by irradiation of the monochromated light from a Xe lamp were detected. As a result, we have succeeded in efficiently enhancing the photocurrent from the porphyrin up to approximately 54 times by tuning the generating wavelength of Cu nanoanntena to the wavelengths above 600 nm, as compared with those generated from the porphyrin-immobilized Cu planar electrode. In a previous study, we reported that the nanoantenna effect from the Au arrayed electrodes enhanced the porphyrin photocurrent up to approximately 15 times.2 Therefore, this study demonstrates that the plasmonic Cu electrodes, which have combined strong light harvesting antenna effect and low material cost, are very useful for improving the performance of organic photoelectric conversion systems. Therefore, this is an important basic research which can accelerate the practical application of highly-efficient plasmonic photoelectric conversion systems.

A Driver Circuit of Spatial Light Modulator

Spatial light modulator (SLM) driving circuit is an important constituent of photoelectric signal conversion system which has a very broad application prospects in various fields such as image display, image recognition, high-speed optical computing and optical communication system. In this study, a high speed and high precision driving circuit was developed, which was applied in 2 level grayscale image processing. This driving circuit adopted Charter .35µm technology. The testing results demonstrated that detection signal was able to follow the driving voltage of modulator and control the modulator on optical signal modulation.