A Novel Dye-Sensitized Solar Cell Structure Based on Metal Photoanode without FTO/ITO

Traditional dye-sensitized solar cells (DSSC) use FTO/ITO containing expensive rare elements as electrodes, which are difficult to meet the requirements of flexibility. A new type of flexible DSSC structure with all-metal electrodes without rare elements is proposed in this paper. Firstly, a light-receiving layer was prepared outside the metal photoanode with small holes to realize the continuous oxidation-reduction reaction in the electrolyte; Secondly, the processing technology of the porous titanium dioxide (TiO2) film was analyzed. By testing the J–V characteristics, it was found that the performance is better when the heating rate is slow. Finally, the effects of different electrode material combinations were compared through experiments. Our results imply that in the case of all stainless-steel electrodes, the open-circuit voltage can reach 0.73 V, and in the case of a titanium photoanode, the photoelectric conversion efficiency can reach 3.86%.

Cross-Scale Synthesis of Organic High-k Semiconductors Based on Spiro-Gridized Nanopolymers

High dielectric constants in organic semiconductors have been identified as a central challenge for the improvement in not only piezoelectric, pyroelectric, and ferroelectric effects but also photoelectric conversion efficiency in OPVs, carrier mobility in OFETs, and charge density in charge-trapping memories. Herein, we report an ultralong persistence length (lp≈41 nm) effect of spiro-fused organic nanopolymers on dielectric properties, together with excitonic and charge carrier behaviors. The state-of-the-art nanopolymers, namely, nanopolyspirogrids (NPSGs), are synthesized via the simple cross-scale Friedel-Crafts polygridization of A2B2-type nanomonomers. The high dielectric constant (k=8.43) of NPSG is firstly achieved by locking spiro-polygridization effect that results in the enhancement of dipole polarization. When doping into a polystyrene-based dielectric layer, such a high-k feature of NPSG increases the field-effect carrier mobility from 0.20 to 0.90 cm2 V-1 s-1 in pentacene OFET devices. Meanwhile, amorphous NPSG film exhibits an ultralow energy disorder (<50 meV) for an excellent zero-field hole mobility of 3.94×10−3 cm2 V−1 s−1, surpassing most of the amorphous π-conjugated polymers. Organic nanopolymers with high dielectric constants open a new way to break through the bottleneck of efficiency and multifunctionality in the blueprint of the fourth-generation semiconductors.

Direct Z-scheme MgIn2S4/TiO2 heterojunction for enhanced photocathodic protection of metals under visible light

To improve the photocathodic protection performance of traditional TiO2 photoanodes for metals, constructing a Z-scheme heterojunction is one of the most promising and creative strategies. Herein, we fabricated a novel Z-scheme MgIn2S4 nanosheets/TiO2 nanotube nanocomposite through anodization and hydrothermal method. The optimized Z-scheme MgIn2S4/TiO2 nanocomposites exhibited stronger visible light absorption, higher separation efficiency of photoelectrons and photocathodic protection performances in comparison to pure TiO2. The theoretical analysis and experimental results show that the Z-scheme heterojunction and oxygen vacancies jointly improved the separation efficiency of photogenerated electron-hole pairs and visible light absorption capacity, thereby improving the photoelectric conversion performance of the MgIn2S4/TiO2 nanocomposites. Furthermore, the influence of the precursor solution concentration on the photocathodic protection performances of the composites was investigated. As a result, when the concentration of magnesium source in the precursor solution was 0.06 mmol, the prepared MgIn2S4/TiO2-0.06 displayed the best photocathodic protection performance. In addition, the hydroxyl radicals (•OH) generated in the electron spin resonance (ESR) experiment verified the Z-scheme heterojunction mechanism of the MgIn2S4/TiO2 composite, and also demonstrated the excellent redox performance of the composite. This work provides valuable reference for the construction of high-performance Z-scheme heterojunctions for photocathode protection of metals.

MPPT Control Strategy of Photovoltaic Cells Based on Duty Cycle Disturbance

Photovoltaic cell is a key part of solar power generation system, and whether its photoelectric conversion is sufficient is also called the maximum power point tracking problem, that is, photovoltaic cell MPPT. Different from the traditional MPPT control algorithm, this paper models and analyzes the output characteristics of solar cell. on this basis, proposes a fuzzy control algorithm based on duty cycle disturbance, and simulates it with MATLAB. The result shows the algorithm can well take into account the tracking speed and control accuracy when the external environment change.

High throughput screening of promising lead-free inorganic halide double perovskites via first-principles calculations

Perovskite solar cells (PSCs) have been intensively investigated and made great progress due to their high photoelectric conversion efficiency and low production cost. However, poor stability and the toxicity of...

Solar cells based on CdTe thin films

An analysis of the use of semiconductor solar cells based on thin-film cadmium telluride (CdTe) in power engineering is carried out. It is shown that the advantages of thin-film technology and CdTe itself as a direct-gap semiconductor open up the prospect of large-scale production of competitive CdTe solar modules. The physical and technical problems of increasing the efficiency of CdS/CdTe heterostructure solar cells, which are significantly inferior to the theoretically possible value in mass production, are discussed. The state of CdTe thin-film solar cells, which make CdTe a suitable material for ground-based photoelectric conversion of solar energy, the historical development of the CdTe compound, the application of CdTe thin films, the main methods and strategies of device production, device analysis and fundamental problems related to the future development of thin-film modules based on cadmium telluride.

CoSe2@N-Doped Graphene Nanocomposite High-Efficiency Counter Electrode For Dye-Sensitized Solar Cells

Photovoltaics is defined as a group of solar cells that convert solar energy into electricity. Among these cells, dye-sensitized solar cells (DSSCs) have received considerable attention due to of their low cost and high efficiency for energy conversion. In present study, CoSe2@N-doped graphene nanocomposite has been prepared in an inert atmosphere and used as a DSSC counter electrode. The fabricated nanocomposite was characterised using analytical techniques including FTIR, TGA, XRD, Raman, XPS, and BET. The assembled DSSC obtains a photoelectric conversion efficiency (PCE) of 7.65%, which is higher than the PCE (7.19%) of the Pt electrode assembly cell under the same conditions. The promising performance of the fabricated counter electrodes may be due to the excellent surface area of the nanocomposites, the doping of hetroatomes which provide the active sites to boost the catalytic activities towards I3- reduction.

One-step route for Z-scheme Al2(WO4)3/Bi2WO6 heterojunction toward superior photoelectric and photocatalytic performance

Herein, Al2(WO[Formula: see text]/Bi2WO6 heterojunctions with [Formula: see text]-type structure were successfully prepared by a one-step hydrothermal method. Moreover, the effects of different composite ratios on the properties of materials were explored. The electrochemical tests and photocatalytic degradation experiments showed that the corresponding Al2(WO[Formula: see text]/Bi2WO6 heterojunctions all exhibited improved electrochemical performance and photocatalytic performance than that of the bare Bi2WO6 material. Especially, when the molar ratio of Al to Bi was 2:1, the obtained Al2(WO[Formula: see text]/Bi2WO6 heterojunction displayed the optimal photoelectric and photocatalytic performance. In detail, it depicted the highest photocurrent density, the smallest resistance and the fastest charge transfer rate. What’s more, the RhB solution (10 ppm) could be completely degraded in 30 min under visible-light irradiation, and the removal rate was almost 1.6 times than that of pure Bi2WO6 nanosheets. In the same condition, it also exhibited excellent photocatalytic performance for the degradation of tetracycline (TC) solution (10 ppm) and the K2Cr2O7 solution (40 ppm). These results fully manifested that the constructed Al2(WO[Formula: see text]/Bi2WO6 heterojunction possessed superior photoelectric conversion capacity and outstanding photocatalytic performance. Moreover, based on the obtained experimental results, a [Formula: see text]-scheme mechanism of catalytic degradation of RhB and TC under simulated solar light was proposed and discussed.

Small reorganization energy acceptors enable low energy losses in non-fullerene organic solar cells

Minimizing the energy loss is of critical importance in the pursuit of attaining high-performance organic solar cells (OSCs). Interestingly, electron-vibration coupling (namely reorganization energy) plays a crucial role in the photo-electric conversion processes. However, a molecular understanding of the relationship between the reorganization energy and the energy loss has rarely been studied. Here, two new acceptors Qx-1 and Qx-2 with quinoxaline (Qx)-containing fused core were designed and synthesized. The results indicate that the reorganization energies of these two acceptors during the photoelectric conversion processes are substantially smaller than the conventional Y6 acceptor, which is beneficial for improving the exciton lifetime and diffusion length, promoting charge transport and reducing the energy loss originating from exciton dissociation and non-radiative recombination. As a result, an outstanding power conversion efficiency (PCE) of 18.2% with high Voc above 0.93 V in the PM6:Qx-2 blend, accompanying a significantly reduced energy loss of 0.48 eV. To the best of our knowledge, the obtained energy loss is the smallest for the binary OSCs with PCEs over 16% reported to date. This work underlines the importance of the reorganization energy in achieving small energy loss in organic active materials and paves a new way to obtain high-performance OSCs.

Effective Double Electron Transport Layer Inducing Crystallization of Active Layer for Improving the Performance of Organic Solar Cells

Interface modification plays an important role in enhancing the photoelectric conversion efficiency and stability of organic solar cells. In this work, alkali metal lithium chloride (LiCl) was introduced between indium tin oxide and polyethyleneimine ethoxylate (PEIE) to prepare a double-layer electron transport layer. Results show that the introduction of LiCl has dual functions. The first function is that LiCl can enhance conductivity, thereby facilitating charge collection. The second function is that the double-layer electron transport layer based on LiCl can induce the crystallization of active layer, thereby enhancing charge transport. Devices with LiCl/PEIE double layer achieve a high power conversion efficiency (PCE) of 3.84%, which is 21.5% higher than that of pristine devices (the PCE of pristine devices with pure PEIE interface layer is 3.16%).