Close packed ZnO nanoparticles on carbon cloth were synthesized by repeating a facile hydrothermal route in this study. After characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), the obtained ZnO cloth was further studied for the applications in lithium (Li)-ion batteries (LIBs) and dye-sensitized solar cells (DSSCs). When ZnO cloth annealed at 400°C for 2 h were used as anodes of LIBs, it exhibited high capacity of 600 mAh/g and outstanding cycling capability without significant fading after 130 cycles. Moreover, it was also found that our electrodes displayed good stabilities under various humidity and temperature. Furthermore, the obtained composites were calcined at higher temperature (800°C) to remove carbon and white pure ZnO cloth was formed. We transferred the as-formed ZnO cloth to?fluorine-doped tin oxide (FTO) substrate to make DSSCs, exhibiting an improved efficiency of around 0.38% assisted by TiCl₄ treatment.

Cu₂ZnSn(S,Se)₄ (CZTSSe) is considered as the promising absorbing layer materials for solar cells due to its earth-abundant constituents and excellent semiconductor properties. Through solution-processing, such as various printing methods, the fabrication of high performance CZTSSe solar cell could be applied to mass production with extremely low manufacturing cost and high yield speed. To better fulfill this goal, environmental-friendly inks/solutions are optimum for further reducing the capital investment on instrument, personnel and environmental safety. In this review, we summarized the recent development of CZTSSe thin films solar cells fabricated with benign solvents, such as water and ethanol. The disperse system can be classified to the true solution (consisting of molecules) and the colloidal suspension (consisting of nanoparticles).Three strategies for stabilization (i.e., physical method, chemical capping and self-stabilization) are proposed to prepare homogeneous and stable colloidal nanoinks. The one-pot self-stabilization method stands as an optimum route for preparing benign inks for its low impurity involvement and simple procedure. As-prepared CZTSSe inks would be deposited onto substrates to form thin films through spin-coating, spraying, electrodeposition or successive ionic layer adsorption and reaction (SILAR) method, followed by annealing in a chalcogen (S- or Se-containing) atmosphere to fabricate absorber. The efficiency of CZTSSe solar cell fabricated with benign solvents can also be enhanced by constituent adjustments, doping, surface treatments and blocking layers modifications, etc., and the deeper research will promise it a comparable performance to the non-benign CZTSSe systems.

Al doped zinc oxide (AZO) films were prepared by mid-frequency magnetron sputtering for silicon (Si) thin film solar cells. Then, the influence of deposition parameters on the electrical and optical properties of the films was studied. Results showed that high conductive and high transparent AZO thin films were achieved with a minimum resistivity of 2.45 × 10^-4 Ω?cm and optical transmission greater than 85% in visible spectrum region as the films were deposited at a substrate temperature of 225°C and a low sputtering power of 160 W. The optimized films were applied as back reflectors in a-SiGe:H solar cells. A relative increase of 19% in the solar cell efficiency was achieved in comparison to the cell without the ZnO films doped with Al (ZnO:Al).

Dye-sensitized solar cells (DSSCs) cannot be developed without the research on sensitizers. As the key of light harvesting and electron generation, thousands of sensitizers have been designed for the application in DSSC devices. Among them, organic sensitizers have drawn a lot of attention because of the flexible molecular design, easy synthesis and good photovoltaic performance. Recently, new record photovoltaic conversion efficiencies of 11.5% for DSSCs with iodide electrolyte and 14.3% for DSSCs with cobalt electrolyte and co-sensitization have been achieved with organic sensitizers. Here we focus on the donor design and modification of organic sensitizers. Several useful strategies and corresponding typical examples are presented.

This paper proposed a new architecture design for nanowire-based quantum-dot-sensitized solar cells to improve the photovoltaic performance. Microstructured rough substrate was used to increase the surface area of the photoanode without influence on charge carrier transport in the system. Compared to conventional devices, the short circuit current density and power conversion efficiency were enhanced by 50%. And the technology can be widely used in the photoelectrochemical (PEC) field, and it can be combined with other hierarchical nanostructures.

Four organic sensitizers containing quinoxaline or benzoxadiazole as an auxiliary electron acceptor in conjugated bridge were synthesized and utilized for dye-sensitized solar cells (DSSCs). It was found that the incorporation of different electron-withdrawing moieties can affect the absorption spectra, electronic properties, the interfacial interactions and then the overall conversion efficiencies significantly. Therefore, the appropriate selection of the auxiliary acceptor was important to optimize the photovoltaic performance of solar cells. Among these sensitizers, LI-44 based solar cell showed the best photovoltaic performance: a shortcircuit photocurrent density (J_sc) of 13.90 mA/cm², an open-circuit photovoltage (V_oc) of 0.66 V, and a fill factor (FF) of 0.66, corresponding to an overall conversion efficiency of 6.10% under standard global AM 1.5 solar light conditions.

This work explores the use of poly(3-hexylthiophene) (P3HT) modified carbon nanotubes (CNTs@P3HT) for the cathodes of hole transporter free, mesoscopic perovskite (CH₃NH₃PbI₃) solar cells (PSCs), simultaneously achieving high-performance, high stability and low-cost PSCs. Here the thin P3HT modifier acts as an electron blocker to inhibit electron transfer into CNTs and a hydrophobic polymer binder to tightly cross-link the CNTs together to compact the carbon electrode film and greatly stabilize the solar cell. On the other hand, the presence of CNTs greatly improve the conductivity of P3HT. By optimizing the concentration of the P3HT modifier (2 mg/mL), we have improved the power conversion efficiencies (PCEs) of CNTs@P3HT based PSCs up to 13.43% with an average efficiency of 12.54%, which is much higher than the pure CNTs based PSCs (best PCE 10.59%) and the sandwich-type P3HT/CNTs based PSCs (best PCE 9.50%). In addition, the hysteresis of the CNTs@P3HT based PSCs is remarkably reduced due to the intimate interface between the perovskite and CNTs@P3HT electrodes. Degradation of the CNTs@ P3HT based PSCs is also strongly retarded as compared to cells employing the pure CNTs electrode when exposed to the ambient condition of 20%-40% humidity.

The importance of methylammonium lead triiodide (CH₃NH₃PbI₃ or MAPbI₃) organic-inorganic hybrid perovskites has shot up dramatically since their use in highly efficient thin-film perovskite solar cells (PSCs). However, the basic structural characterization of these fascinating materials remains sparse. In particular, Raman spectroscopy, which is a powerful vibrational spectroscopy characterization tool and complements other characterization methods, of MAPbI₃ under ambient conditions is plagued with difficulties. Here, a systematic ambient Raman spectroscopy characterization study of MAPbI₃ thin films is conducted under different conditions (excitation laser wavelength, integration time, filter characteristic). The results from this study help elucidate the possible sources of artifacts in the Raman spectra, and raise the awareness of the challenges in the ambient Raman spectroscopy of MAPbI₃ perovskites. Approaches to overcome these challenges are suggested.

In this paper, via numerical simulation we designed the geometry of solar cell made by one-dimensional (1D) and two-dimensional (2D) photonic crystals with two kinds of materiel (silicon (Si) and hydrogenated amorphous silicon (a-Si:H)) in order to enhance its absorption. The absorption characteristics of light in the solar cell structures are simulated by using finite-difference time-domain (FDTD) method. The calculation results show that the enhancement of absorption in patterned structure is apparent comparing to the unpatterned one, which proves the ability of the structure to produce photonic crystal solar cell. We found solar cell geometries as a 2D photonic crystal enable to increase the absorption between 380 and 750 nm.

In this paper, influence of temperature and reverse bias on photocurrent spectrum and spectral response of a monolithic GaInP/GaAs double-junction solar cell was investigated in detail. Two sharp spectral response offsets, corresponding to the bandedge photo absorption of the bottom GaAs and the top GaInP subcells, respectively, show the starting response points of individual subcells. More interestingly, the cell photocurrent was found to enhance significantly with increasing the temperature. In addition, the cell photocurrent also increases obviously as the reverse bias voltage increases. The integrated photocurrent intensity of the top GaInP subcell was particularly addressed. A theoretical model was proposed to simulate the reverse bias dependence of the integrated photocurrent of the GaInP subcell at different temperatures.

Textured surface boron-doped zinc oxide (BZO) thin films were fabricated by metal organic chemical vapor deposition as transparent conductive oxide (TCO) for solar cells. The surface microstructure was characterized by X-ray diffraction spectrum and scanning electron microscope. The optical transmittance was shown by optical transmittance microscope and the electrical properties were tested by Hall measurements. The thickness of the BZO film has crucial impact on the surface morphology, optical transmittance, and resistivity. The electrical and optical properties as well as surface microstructure varied inconsistently with the increase of the film thickness. The grain size and the surface roughness increased with the increase of the film thickness. The conductivity increased from 0.96×10³ to 6.94×10³ S/cm while the optical transmittance decreased from above 85% to nearly 80% with the increase of film thickness from 195 to 1021 nm. The BZO films deposited as both front and back transparent electrodes were applied to the bifacial p-type a-Si:H/i-type a-Si:H/n-type c-Si/i-type a-Si:H/n⁺-type a-Si:H heterojunction solar cells to obtain the optimized parameter of thickness. The highest efficiency of all the samples was 17.8% obtained with the BZO film thickness of 829 nm. Meanwhile, the fill factor was 0.676, the open-circuit voltage was 0.63 V and the short-circuit density was 41.79 mA/cm². The properties of the solar cells changing with the thickness were also investigated.

Mixed lead-tin (Pb-Sn) perovskites present a promising strategy to extend the light-harvesting range of perovskite-based solar cells (PSCs). The use of electron-transporting layer or hole-transporting layer (HTL) is critical to achieve high device efficiency. This strategy, however, requires tedious layer-by-layer fabrication as well as high-temperature annealing for certain oxides. In this work, we fabricated HTL-free planar FAPb_0.5Sn_0.5I₃ PSCs with the highest efficiency of 7.94%. High short-circuit current density of 23.13 mA/cm² was attained, indicating effective charge extraction at the ITO/FAPb_0.5Sn_0.5I₃ interface. This finding provides an alternative strategy to simplify the manufacture of single-junction or tandem PSCs.

Efficient indium tin oxide (ITO)-free inverted polymer solar cells (PSCs) were fabricated by applying ultrathin metal transparent electrodes as sunlight incident electrodes. Smooth and continuous Ag film of 4 nm thickness was developed through the introduction of a 2 nm Au seed layer. Ultrathin Ag transparent electrode with an average transmittance of up to 80% from 480 to 680 nm and a sheet resistance of 35.4 W/sq was obtained through the introduction of a ZnO anti-reflective layer. The ultrathin metal electrode could be directly used as cathode in polymer solar cells without oxygen plasma treatment. ITO-free inverted PSCs obtained a power conversion efficiency (PCE) of 5.2% by utilizing the ultrathin metal transparent electrodes. These results demonstrated a simple method of fabricating ITO-free inverted PSCs.

The rapid deployment of solar and wind technology produces significant amount of low-quality electricity that calls for a better storage or usage instead of being discarded by the grid. Instead of electrochemical CO₂ reduction and/or NH₃ production, here we propose that non-thermal plasma oxidation of N₂ into nitrate or other valuable nitrogen containing compounds deserve more research attention because it uses free air as the reactant and avoids the solubility difficulty, and also because its energy consumption is merely 0.2 MJ/mol, even lower than the industrially very successful Haber–Bosch process (0.48 MJ/mol) for NH₃ production. We advocate that researchers from the plasma community and chemistry community should work together to build energy efficient non-thermal plasma setup, identify robust, active and low-cost catalyst, and understand the catalyzing mechanism in a plasma environment. We are confident that free production of nitrate with zero CO₂ emission will come true in the near future.