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Dye-sensitized solar cells (DSCs) convert light into electricity by using photosensitizers adsorbed on the surface of nanocrystalline mesoporous titanium dioxide (TiO2) films along with electrolytes or solid charge-transport materials1–3. They possess many features including transparency, multicolour and low-cost fabrication, and are being deployed in glass facades, skylights and greenhouses4. Recent development of sensitizers5–10, redox mediators11–13and device structures14has improved the performance of DSCs, particularly under ambient light conditions14–17. To further enhance their efficiency, it is pivotal to control the assembly of dye molecules on the surface of TiO2to favour charge generation. Here we report a route of pre-adsorbing a monolayer of a hydroxamic acid derivative on the surface of TiO2to improve the dye molecular packing and photovoltaic performance of two newly designed co-adsorbed sensitizers that harvest light quantitatively across the entire visible domain. The best performing cosensitized solar cells exhibited a power conversion efficiency of 15.2% (which has been independently confirmed) under a standard air mass of 1.5 global simulated sunlight, and showed long-term operational stability (500 h). Devices with a larger active area of 2.8 cm2exhibited a power conversion efficiency of 28.4% to 30.2% over a wide range of ambient light intensities, along with high stability. Our findings pave the way for facile access to high-performance DSCs and offer promising prospects for applications as power supplies and battery replacements for low-power electronic devices18–20that use ambient light as their energy source.

Long-term durability is critically important for the commercialization of perovskite solar cells (PSCs). The ionic character of the perovskite and the hydrophilicity of commonly used additives for the hole-transporting layer (HTL), such as lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) and tert-butylpyridine (tBP), render PSCs prone to moisture attack, compromising their long-term stability. Here we introduce a trifluoromethylation strategy to overcome this drawback and to boost the PSC’s solar to electric power conversion efficiency (PCE). We employ 4-(trifluoromethyl)benzylammonium iodide (TFMBAI) as an amphiphilic modifier for interfacial defect mitigation and 4-(trifluoromethyl)pyridine (TFP) as an additive to enhance the HTL’s hydrophobicity. Surface treatment of the triple-cation perovskite with TFMBAI largely suppressed the nonradiative charge carrier recombination, boosting the PCE from 20.9% to 23.9% and suppressing hysteresis, while adding TFP to the HTL enhanced the PCS’s resistance to moisture while maintaining its high PCE. Taking advantage of the synergistic effects resulting from the combination of both fluoromethylated modifiers, we realize TFMBAI/TFP-based highly efficient PSCs with excellent operational stability and resistance to moisture, retaining over 96% of their initial efficiency after 500 h maximum power point tracking (MPPT) under simulated 1 sun irradiation and 97% of their initial efficiency after 1100 h of exposure under ambient conditions to a relative humidity of 60–70%.

Three new tris-heteroleptic complexes of ruthenium(II) were designed by coordinating the metal center with cyclometalating, anchoring, and auxiliary ligands with different donor substituents. N-Hexylcarbazole, N-hexylphenothiazine, and N-hexyldiphenylamine donor moieties were used as substituents on the auxiliary ligands for SA633, SA634, and SA635, respectively. Complexes were characterized by 1H and 13C 2D-COSY NMR techniques. These complexes provide power conversion efficiencies in the range of 7.6–8.2% when they are employed in state of the art dye-sensitized solar cells (DSCs) with cobalt electrolyte. Various electrochemical and transient techniques were used to unveil the unexpected differences in the performance of these very similar sensitizers.

We report a blue dye, coded as R6, which features a polycyclic aromatic hydrocarbon, 9,19-dihydrobenzo[1′,10′]phenanthro[3′,4′:4,5]thieno[3,2-b]benzo[1,10]phenanthro[3,4-d]thiophene, coupled with a diarylamine electron donor and 4-(7-ethynylbenzo[c][1,2,5]thiadiazol-4-yl)benzoic acid acceptor. Dye R6 displays a brilliant sapphire color in a sensitized TiO2mesoporous film with a Co(II/III) tris(bipyridyl)-based redox electrolyte. The R6 based dye-sensitized solar cell achieves an impressive power conversion efficiency of 12.6% under standard air mass 1.5 global, 100 mW cm–2, and shows a remarkable photostability.

In this article, we report two metal-free perylene dyes (C269and C270) featuring the electron acceptors benzothiadiazole–benzoic acid and ethynylbenzothiadiazole–benzoic acid, respectively, in combination with a bis(4-(hexyl)phenyl)amino-capped N-annulated perylene (NP) electron donor. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations revealed that the use of ethynylbenzothiadiazole–benzoic acid can lower the level of the lowest unoccupied molecular orbital (LUMO), reduce the energy gap, and attenuate the Stokes shift of an NP dye. These effects are in good accord with electrochemical and photophysical measurements. When used in sensitized titania solar cells, C270dye exhibits a reasonably good power conversion efficiency close to 9% at an irradiance of 100 mW cm–2simulated AM1.5 sunlight. It was also found that, with respect to C269, C270dye forms a thinner and looser self-assembled dye layer on the surface of titania, accounting for the shorter electron lifetime and lower open-circuit photovoltage for cells made with C270. Our femtosecond transient absorption (fs-TA) measurements confirmed a positive relationship between the driving energy and electron-injection rate despite the close-to-unity electron-injection yields for both dyes. In addition, the target analysis of fs-TA data indicated that, with respect to C269, more electrons are injected from the relaxed excited states for C270dye with a lower LUMO level.

We synthesize two new metal-free donor–acceptor organic dyes (C266and C267) featuring a N-annulated perylene block. Owing to the improved coplanarity of conjugated units as well as the prolonged conjugation upon inserting a triple bond between the triarylamine and perylene segments, the C267dye exhibits a slightly red-shifted absorption peak and an enhanced maximum molar absorption coefficient with respect to its reference dye C266, leading to an improved photocurrent output in dye-sensitized solar cells. However, the triple-bond introduction also brings forth an over 100 mV reduced open-circuit photovoltage owing to faster interfacial charge recombination, which presents a clear correlation with a reduced mean thickness of self-assembled dye layer on titania as revealed by X-ray reflectivity measurements. The C266dye, albeit with a relatively weaker light-harvesting capacity, displays a higher power conversion efficiency of 9.0% under the 100 mW cm–2, simulated AM1.5G sunlight.

In this article, TiO2–Carbon–rGO (GCT) three-component composite material has been constructed by anchoring TiO2nanoparticles (NPs) encapsulated in carbon shells onto reduced graphene oxide (rGO) sheets. The structure of GCT was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), N2adsorption–desorption isotherms, and transmission electron microscopy (TEM). This material shows a superior retention as the anode materials in lithium ion battery with a specific discharge capacity of 188 mA h g–1in the initial cycle and 158 mA h g–1after 100 cycles.

Most photovoltaic (PV) technologies are opaque to maximize visible light absorption. However, see-through solar cells open additional perspectives for PV integration. Looking beyond maximizing visible light harvesting, this work considers the human eye photopic response to optimize a selective near-infrared sensitizer based on a polymethine cyanine structure (VG20-Cx) to render dye-sensitized solar cells (DSSCs) fully transparent and colorless. This peculiarity was achieved by conferring to the dye the ability to strongly and sharply absorb beyond 800 nm (S0–S1transition) while rejecting the upper S0–Sncontributions far in the blue where the human retina is poorly sensitive. When associated with an aggregation-free anatase TiO2photoanode, the selective NIR-DSSC can display 3.1% power conversion efficiency, up to 76% average visible transmittance (AVT), a value approaching the 78% AVT value of a standard double glazing window while reaching a color rendering index (CRI) of 92.1%. The ultrafast and fast charge transfer processes are herein discussed, clarifying the different relaxation channels from the dye monomer excited states and highlighting the limiting steps to provide future directions to enhance the performances of this nonintrusive NIR-DSSC technology.