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Abstract The co-sensitization of mesoscopic TiO 2 anode is a promising solution to wide-spectra dye-sensitized solar cells (DSSCs) with improved power conversion efficiency. Quantum dots are featured with tunable bandgaps, small sizes and high absorption coefficients, therefore they are always combined with state-of-the-art organic dyes for co-sensitized solar cells. We present here the sonochemistry-assisted synthesis of hybrid black/red phosphorus quantum dots (BP/RPQDs) for DSSC applications. The preliminary results demonstrate that hybrid BP/RPQDs have prolonged recombination lifetime of photogenerated carriers and light-response from ultraviolet to visible and even near-infrared (NIR) region. Upon assembly into liquid-junction DSSCs, the devices with BP/RPQDs-only and BP/RPQDs-N719 co-sensitizer achieve efficiencies of 0.12% and 8.02% in comparison with 7.60% for N719-only solar cell. Using photofluorescent photoanode from mesoscopic TiO 2 and long-persistence phosphor (LPP), the new-typed DSSC presents persistent power generation performances after ceasing simulated sunlight irradiation. Graphical abstract Image 1 Highlights • Hybrid BP/RPQDs are made by a sonochemistry-assisted method. • The hybrid BP/RPQDs show wide light-response in light-harvesters of DSSCs. • BP/RPQDs-only solar cells show a PCE of 0.12%. • An efficiency as high as 8.02% is achieved for BP/RPQDs tailored DSSCs. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cells (DSSC) have narrow spectral response and serious electron-hole recombination, which are two burdens for photovoltaic performance enhancement. In order to make high-performance DSSCs featured by wide-spectral absorption and fast charge extraction, we present here experimental realization of co-sensitization of nitrogen (N)-doped carbon quantum dots (N-CQDs) with N719 dye. Arising from up-conversion and hole extraction behaviors of N-CQDs, a maximized power conversion efficiency (PCE) as high as 9.29% under one sun illumination is achieved for N 300 -CQDs/N719 co-sensitized DSSC in comparison with 8.09% for N 300 -CQDs-free device. Due to light storing and emitting characteristics of photofluorescent long persistence phosphors in mesoscopic titanium dioxide/long persistence phosphor ( m -TiO 2 /LPP) photoanode, electricity is persistently generated when ceasing sunlight illumination. This work is far from optimization, but the physical proof-of-concept co-sensitization and fast charge extraction may remarkably widen light-response windows and promote electron-hole separation for advanced photovoltaic devices. [ABSTRACT FROM AUTHOR]

Photovoltaics are regarded as the promising solution to resolve energy and environmental problems owing to their high power conversion efficiency and zero emissions. However, the narrow-spectra absorption range and serious recombination reactions at electrode/electrolyte interfaces are two major drawbacks for high-performance solar cells. Herein, a new way of synthesizing organic-inorganic hybrid CH 3 NH 3 PbX 3 (X = Cl, Br or I) perovskite quantum dots (PQDs) is demonstrated by dropping perovskite precursor solution into anhydrous toluene. After a systematic study, the results demonstrate that the energy levels of PQDs can be tuned through optimizing the stoichiometric ratio of halide ions, showing good optical properties for photovoltaic applications. A quasi-solid-state sensitized solar cell with configuration of FTO/ m -TiO 2 /PQDs/dye/long persistence phosphor/gel electrolyte/Pt/FTO is fabricated, yielding an impressive power conversion efficiency as high as 7.91%, which is higher than 7.26% for referenced device free of PQDs. The improved performances are mainly attributed to the increased light absorption as well as reduced recombination upon the incorporation of PQDs and long persistence phosphor into devices. [ABSTRACT FROM AUTHOR]

Bifacial dye-sensitized solar cells (DSSCs) are regarded as promising photovoltaics to harvest solar energy from both front and rear sides because of their significantly increased total power outputs. Transparent counter electrodes (CEs) with cost-effectiveness and high electrocatalytic activity are crucial to make these high-performance bifacial devices. Herein, a category of transparent CEs from ternary alloys [(CoM) 0.85 Se, M = Ni, Ru, Fe] are synthesized by a mild solution method. Upon careful optimization on optical behaviors, electrocatalytic activity and photovoltaic performances, the bifacial DSSCs with (CoNi) 0.85 Se, (CoRu) 0.85 Se, (CoFe) 0.85 Se CEs achieve front power conversion efficiencies of 9.14%, 8.09%, 7.58% and rear efficiencies of 3.86%, 3.31%, 3.51% in comparison with 6.72% and 3.16% for state-of-the-art Pt CE based solar cell, respectively. Moreover, these bifacial DSSCs devices display high multiple on/off capability and relatively good stability. [ABSTRACT FROM AUTHOR]

Bifacial light-harvesting technology is regarded as one effective strategy to enhance the power output of photovoltaic devices, in which the transparent electrode is crucial to determine the power conversion efficiency when illuminated from rear side. To date, the efficiency enhancement of the state-of-the-art bifacial mesoscopic solar cells is mainly focused on the rational design of high catalytic counter electrode without sacrificing the transparency. The cell performance maximum through increasing electron density at counter electrode surface to enhance its catalytic ability is still a challenging problem. In the current work, bi-tandem carbon quantum dots are made to tailor transparent CoSe counter electrode for bifacial dye-sensitized solar cells, achieving a maximized front power conversion efficiency of 8.54% and a rear efficiency of 6.55% in comparison with 7.87% and 5.03% for carbon quantum dots-free device, respectively. The mechanism behind this increment is stemmed from the photo-excited electrons of bi-tandem carbon quantum dots and therefore realizing the electron accumulation on the counter electrode surface. [ABSTRACT FROM AUTHOR]

Dye-sensitized solar cell (DSSC) is a promising solution to relieve global energy crisis and environmental issues because of its superiority in low cost, easy fabrication procedures and relatively high efficiency. The decrease of fabrication cost without sacrifice of power conversion efficiency of the DSSCs can doubtlessly contribute to its commercial application. Here we report a new Pt-free RuCoSe ternary alloy counter electrode (CE) by electrodepositing. The DSSC device with RuCoSe ternary alloy CE achieves a power conversion efficiency of 9.07%, which is higher than 7.03% from Pt-only CE based DSSC. The easy preparation method and promising results provide a new method for decreasing cost but enhancing photovoltaic performance of DSSCs. [ABSTRACT FROM AUTHOR]

Bifacial photovoltaics are promising devices for significantly harvesting solar energy and generating power from either front or rear side. We present here the fabrication of new category of high-performance bifacial dye-sensitized solar cells (DSSCs) tailored with transparent S-doped carbon quantum dots (S-CQDs)/metal selenide counter electrodes. Arising from photoexcitation of S-CQDs and therefore increased electron density at electrode surfaces, the catalytic ability of S-CQDs tailored counter electrodes is markedly enhanced under solar irradiation. The bifacial DSSCs yield maximized front and rear efficiencies of 9.15% and 6.26%, respectively. [ABSTRACT FROM AUTHOR]

Graphical abstract Co/Se and Ni/Se nanocomposite films deposited on FTO glasses via magnetron sputtering are used as counter electrodes in dye-sensitized solar cells, yielding a maximized power conversion efficiency of 6.43%. Highlights: • Co/Se and Ni/Se nano-films are prepared by magnetron sputtering method. • The as-prepared films are employed as CEs for DSSCs. • The DSSC with Co/Se CE delivers a PCE of 6.43%. Abstract Dye-sensitized solar cells are promising solutions to energy and environmental problems. By addressing the high cost of preferred platinum counter electrode, Co/Se and Ni/Se nanocomposite counter electrodes are prepared by magnetron sputtering targets onto fluorine-doped tin oxide glass for dye-sensitized solar cell applications. The binary nanocomposite counter electrodes exhibit superior electrocatalytic activity toward I 3 − reduction compared to pure Ni, Se and Co electrodes. In particular, the dye-sensitized solar cell based on Co/Se counter electrode achieves a power conversion efficiency of 6.43%, which is much higher than 0.87%, 2.91%, 3.77% and 5.23% for Ni, Se, Co and Ni/Se solar cells, respectively. The preliminary results demonstrate it is a promising strategy to prepare robust counter electrodes by magnetron sputtering technique for dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

The development of weather-independent photovoltaics is a persistent goal for energy technique. Herein we develop a category of hybridized dye-sensitized solar cells (DSSCs) from cost-effective poly(3,4-ethylenedioxythiophene) (PEDOT) derivate counter electrodes and mesoscopic titanium dioxide/long persistence phosphors ( m -TiO 2 /LPPs) composite photoanodes. Using the solar energy storage and emission performances of LPP phosphors, the final m -TiO 2 /LPPs photoanodes are demonstrated to store unabsorbed incident light and to persistently emit monochromatic light for re-exciting photosensitizers. The optimized photovoltaics yield a maximized power conversion efficiency of 10.07% under simulated sunlight irradiation (100 mW cm −2 , air mass 1.5 global) and durable energy output lasting for hours when ceasing solar illumination. The application of m -TiO 2 /LPP photoanodes in the hybridized DSSCs provides new opportunities of making multi-energy integrated photovoltaics for persistent power generation free of sun illumination. [ABSTRACT FROM AUTHOR]

Abstract The development of weather-independent photovoltaics is a promising strategy for persistently generating electricity in daytime and night. Herein we build a category of multi-energy integrated bifacial solar cells by making long persistence phosphors (LPPs) tailored transparent counter electrodes. The optimized cell with green-emitting transparent polypyrrole-graphene/PtCo achieves a maximized power conversion efficiency of 8.59% under a simulated sun irradiation (100 mW cm−2, air mass 1.5 global) as well as a dark efficiency of 29.68% when ceasing solar illumination. Moreover, the newly launched photovoltaics can persistently generate power lasting for hours in the dark environments. The current work demonstrates a predictable application of photoelectric engineering for persistent energy harvesting free of sun illumination in future. Graphical abstract Image 1 Highlights • Bifacial DSSCs are made by LPP tailored PPy-graphene/PtCo CE. • LPP releases fluorescence to persistently excite dyes when ceasing sunlight illumination. • The DSSCs can persistently generate electricity in the dark. • The newly launched DSSCs yield maximized dark efficiency as high as 29.68%. [ABSTRACT FROM AUTHOR]

Abstract Developing efficient and cost-effective counter electrodes (CEs) to catalyze triiodide reduction reaction is a persistent objective for high-performance dye-sensitized solar cells (DSSCs). One promising solution is to design electron-enriched electrode materials by combining conductive polymers with alloys. In this work, ternary hybrid PtM@polyaniline (M = Ni, FeNi) CEs are synthesized by one-step replacement reaction and in-situ polymerization reaction. When assembling into liquid-junction DSSCs, the power conversion efficiencies of 8.52% and 8.39% for the devices tailored with PtNi@polyaniline and PtFeNi@polyaniline CEs can be obtained. The experimental results demonstrate that the enhanced photovoltaic performances are mainly attributed to matching work function and high electrocatalytic activity of these well-designed hybrid CEs. Arising from the competitive reactions between transition metal and I 2 /I 3 − species, the dissolution reaction of Pt in liquid electrolyte is restricted and therefore the long-term stability of corresponding devices are significantly enhanced. Graphical abstract Image 1 Highlights • Ternary hybrid PtM@PANi CEs are prepared by one-step method. • Ternary hybrid PtM@PANi CEs are used for DSSC applications. • The hybrid CEs present matching work functions and enhanced catalytic activities. • The device yields a maximized PCE of 8.52% under one sun illumination. [ABSTRACT FROM AUTHOR]

Development of high-performance light harvesters is a persistent goal for mesoscopic solar cells. In the current work, lead-free CH 3 NH 3 SnBr 3-x I x (x = 0–3) perovskite quantum dots (QDs) are made by integrating Br − ions into host crystal structure. Through tuning Br/I ratio, these perovskite-structured QDs are highlighted with tunable optical bandgaps. When applied as light harvesters for mesoscopic solar cell applications, the devices yield reasonable power conversion efficiency and rapid start-up behaviors. An efficiency of 8.79% is achieved for CH 3 NH 3 SnBr 3-x I x QDs and N719 co-sensitized mesoscopic solar cells. [ABSTRACT FROM AUTHOR]