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Dye-sensitized solar cell (DSSC) is a promising solution to global energy and environmental problems because of its clean, low-cost, high efficiency, good durability and easy fabrication. However, enhancing the efficiency of the DSSC still is an important issue. Here we devise a bifacial DSSC based on a transparent polyaniline (PANI) counter electrode (CE). Owing to the sunlight irradiation simultaneously from the front and the rear sides, more dye molecules are excited and more carriers are generated, which results in the enhancement of short-circuit current density and therefore overall conversion efficiency. The photoelectric properties of PANI can be improved by modifying with 4-aminothiophenol (4-ATP). The bifacial DSSC with 4-ATP/PANI CE achieves a light-to-electric energy conversion efficiency of 8.35%, which is increased by ~24.6% compared to the DSSC irradiated from the front only. This new concept along with promising results provides a new approach for enhancing the photovoltaic performances of solar cells.

Solution-processed perovskite photovoltaics promise low-cost, lightweight, and wearable power sources. Processing techniques play a crucial role in this field. Here, we introduce a large-area, patternable, and cyclable film writing technique that utilizes marker pen as a fabrication tool. By adjusting ink concentration, pressure, writing speed, tip width, solvent engineering, and using fiber-capillary structure of marker pens, we demonstrate control over perovskite ink colloids, film thickness (from 200 to > 1000 nm) and area (from 1 to 100+ cm 2 ) patterning on rigid and flexible substrates, as well as ambient writing of crystalline perovskite film. Marker pen written rigid and flexible carbon-electrode perovskite solar modules in mask- and laser-free manners achieve 16.3% and 14.5% power conversion efficiencies, respectively. This method offers an opportunity for rapid on-site fabrication of lightweight and deformable power sources on various substrates, including inflated elastic balloons and folded cellophane paper, and produces customizable irregular solar modules. Solution-processed perovskite photovoltaics hold promises for low-cost and lightweight power sources. Here, the authors utilize a marker pen as a fabrication tool to produce large-area, patternable, and cyclable film, and demonstrate flexible solar modules and power sources on flexible substrates.

Molybdenum disulfide (MoS 2 ) and polyaniline (PANI) electrodes were decorated with multi-walled carbon nanotubes (MWCNTs) on the basis of a facial hydrothermal and in situ polymerization methods and served in the asymmetric supercapacitor (ASC). The MoS 2 and MWCNTs with a mole ratio of 1:1 in MoS 2 |MWCNTs electrode exhibited better electrochemical properties through extensive electrochemical studies, in terms of the highest specific capacitance of 255.8 F/g at 1 A/g, low internal resistance, and notable electrochemical stability with retention of the initial specific capacitance at 91.6% after 1000 cycles. The as-prepared PANI|MWCNTs electrode also exhibited good specific capacitance of 267.5 F/g at 1 A/g and remained 97.9% capacitance retention after 1000 cycles. Then, the ASC with MoS 2 |MWCNTs and PANI|MWCNTs composite electrodes were assembled with polyvinyl alcohol (PVA)-Na 2 SO 4 gel electrolyte, which displayed good electrochemical performance with the specific capacitance of 138.1 F/g at 1 A/g, and remained the energy density of 15.09 Wh/kg at a high power density of 2217.95 W/kg. This result shows that this ASC device possesses excellent electrochemical properties of high energy density and power output and thus showing a potential application prospect.

A ternary and composite MoIn2S4@CNTs counter electrode (CE) with a hedgehog ball structure was synthesized by using a facile one-step hydrothermal method. The composite MoIn2S4@CNTs film possesses large specific surface area through N2 adsorption-desorption isotherms test, which is advantageous to adsorb more electrolyte and provide larger active contact area for the electrode. In addition, the composite MoIn2S4@CNTs CE exhibits low charge transfer resistance and fine electrocatalytic ability made from a series of electrochemical tests including cyclic voltammetry, electrochemical impedance, and Tafel curves. Under optimal conditions, the DSSC based on the MoIn2S4@CNTs-2 composite CE achieves an impressive power conversion efficiency as high as 8.38%, which remarkably exceeds that of the DSSCs with the MoIn2S4 CE (7.44%) and the Pt electrode (8.01%). The current work provides a simplified preparation process for the DSSCs.

The development of low‐cost, green, and pollution‐free counter electrode materials with high catalytic activity plays a critical role in improving the photovoltaic performance of dye‐sensitized solar cells (DSSCs). In recent years, transition metal phosphides have been widely used in DSSCs due to their outstanding catalytic activity and stability. Herein, a novel binary phosphide is immobilized on carbon paper (CP) by a two‐step strategy. This strategy involves the preparation of WO3 precursor by the hydrothermal method, and synthesis of tungsten phosphide (WP) with the vapor deposition method, which finally leads to the uniform dispersion of WP on carbon paper. The acquired WP/CP counter electrode demonstrates high electrical conductivity and prefect catalytic ability for reducing triiodide, and the DSSCs assembled with WP/CP counter electrode achieve a high‐power conversion efficiency of 10.29%, which is superior to that of the Pt‐based (7.34%). These findings illustrate that the WP microsheets in‐situ grown on carbon paper are a potential candidate to replace Pt as an economical and efficient counter electrode for DSSCs. A counter electrode (CE) of anchor tungsten phosphide (WP) onto carbon fibers of carbon paper (CP) is designed to form a heterojunction structure and served as CE for DSSCs, and exhibits much higher photovoltaic performance of DSSC with WP/CP‐3 CE (10.29%) than that of the Pt configuration device (7.34%).

Defect passivation management of perovskite films is of great importance in improving the performance of perovskite solar cells. Various in situ or post-passivation strategies were adopted to modify the optoelectric properties of perovskite films. However, these modifications increased the fabrication complexity and cost of the devices. Here, we developed a facile self-passivation strategy to effectively decrease charge trap states and suppress the non-radiative recombination loss in perovskite films. By simply aging the precursor solution, we found that the fabricated perovskite films possess residual PbI 2 phase that could decrease trap density, enhance the radiative recombination intensity, and facilitate charge transfer and collection. Therefore, the solar cells with this self-passivated perovskite film generated an increased efficiency of 21.1% compared to that of 19.9% for the control devices from fresh precursor solution. Graphical abstract

In order to enhance the photovoltaic performance of dye-sensitized solar cell (DSSC), a novel design is demonstrated by introducing rare-earth compound europium ion doped yttrium fluoride (YF 3 :Eu 3+ ) in TiO 2 film in the DSSC. As a conversion luminescence medium, YF 3 :Eu 3+ transfers ultraviolet light to visible light via down-conversion and increases incident harvest and photocurrent of DSSC. As a p-type dopant, Eu 3+ elevates the Fermi level of TiO 2 film and thus heightens photovoltage of the DSSC. The conversion luminescence and p-type doping effect are demonstrated by photoluminescence spectra and Mott-Schottky plots. When the ratio of YF 3 :Eu 3+ /TiO 2 in the doping layer is optimized as 5 wt.%, the light-to-electric energy conversion efficiency of the DSSC reaches 7.74%, which is increased by 32% compared to that of the DSSC without YF 3 :Eu 3+ doping. Double functions of doped rare-earth compound provide a new route for enhancing the photovoltaic performance of solar cells.

A dye-sensitized and flexible TiO 2 fiber with multilayer structure was prepared by using brush method as the photoanode in the efficient flexible fibrous dye-sensitized solar cells (FFDSSCs) to avoid electronic recombination and improve the electronic capture efficiency. The composite Pt counter electrode, preparation from the surface modification of the electrodeposited Pt wire by using a simple one-step thermal decomposition approach of H 2 PtCl 6 isopropanol and n-butyl alcohol (volume ratio = 1:1) solution, provided a significant improvement in electrocatalytic activity, which was confirmed by extensive electrochemical tests. The FFDSSC assembled with the fiber-shaped TiO 2 photoanode and the composite Pt counter electrode achieves an enhanced photoelectric conversion efficiency of 6.35%, higher than that of the FFDSSC with monolayer fibrous TiO 2 photoanode and electrodeposited Pt wire counter electrode. More importantly, the photoelectric conversion efficiency of 6.35% is comparable to that of the FFDSSC based on the pure Pt wire counter electrode (6.32%). The FFDSSC with high elasticity, flexibility, and stretchability can adapt to complex mechanical deformations, which is of great significance for the development of wearable electronics in the future.

We report a new method as UV treatment of low-temperature processed to obtain tin oxide (SnO 2 ) electron transport layers (ETLs). The results show that the high quality of ETLs can be produced by controlling the thickness of the film while it is treated by UV. The thickness is dependent on the concentration of SnO 2 . Moreover, the conductivity and transmittance of the layer are dependent on the quality of the film. A planar perovskite solar cell is prepared based on this UV-treated film. The temperatures involved in the preparation process are less than 90 °C. An optimal power conversion efficiency of 14.36% is obtained at the concentration of SnO 2 of 20%. This method of UV treatment SnO 2 film at low temperature is suitable for the low-cost commercialized application.

Here we present an ultraviolet responsive inorganic-organic hybrid solar cell based on titania/poly(3-hexylthiophene) (TiO 2 /P3HT) heterojuction. In this solar cell, TiO 2 is an ultraviolet light absorber and electronic conductor, P3HT is a hole conductor, the light-to-electrical conversion is realized by the cooperation for these two components. Doping ionic salt in P3HT polymer can improve the photovoltaic performance of the solar cell. Under ultraviolet light irradiation with intensity of 100 mW·cm −2 , the hybrid solar cell doped with 1.0 wt.% lithium iodide achieves an energy conversion efficiency of 1.28%, which is increased by 33.3% compared to that of the hybrid solar cell without lithium iodide doping. Our results open a novel sunlight irradiation field for solar energy utilization, demonstrate the feasibility of ultraviolet responsive solar cells and provide a new route for enhancing the photovoltaic performance of solar cells.