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The investigation of innovative electrolytes based on nontoxic and nonflammable solvents is an up-to-date, intriguing challenge to push forward the environmental sustainability of dye-sensitized solar cells (DSSCs). Water is one of the best choices, thus 100% aqueous electrolytes are proposed in this work, which are gelled with xanthan gum. This well-known biosourced polymer matrix is able to form stable and easily processable hydrogel electrolytes based on the iodide/triiodide redox couple. An experimental strategy, also supported by the multivariate chemometric approach, is used here to study the main factors influencing DSSCs efficiency and stability, leading to an optimized system able to improve its efficiency by 20% even after a 1200 h aging test, and reaching an overall performance superior to 2.7%. In-depth photoelectrochemical investigation demonstrates that DSSCs performance based on hydrogel electrolytes depends on many factors (e.g., dipping conditions, redox mediator concentrations, etc.), that must be carefully quantified and correlated in order to optimize these hydrogels. Photovoltaic performances are also extremely reproducible and stable in an open cell filled in air atmosphere, noticeably without any vacuum treatments.

Despite considerable research efforts on photoelectrochemical water splitting over the past decades, practical application faces challenges by the absence of efficient, stable, and scalable photoelectrodes. Herein, we report a metal-halide perovskite-based photoanode for photoelectrochemical water oxidation. With a planar structure using mesoporous carbon as a hole-conducting layer, the precious metal-free FAPbBr 3 photovoltaic device achieves 9.2% solar-to-electrical power conversion efficiency and 1.4 V open-circuit voltage. The photovoltaic architecture successfully applies to build a monolithic photoanode with the FAPbBr 3 absorber, carbon/graphite conductive protection layers, and NiFe catalyst layers for water oxidation. The photoanode delivers ultralow onset potential below 0 V versus the reversible hydrogen electrode and high applied bias photon-to-current efficiency of 8.5%. Stable operation exceeding 100 h under solar illumination by applying ultraviolet-filter protection. The photothermal investigation verifies the performance boost in perovskite photoanode by photothermal effect. This study is significant in guiding the development of photovoltaic material-based photoelectrodes for solar fuel applications. Lead halide perovskites excel in optical and electronic properties, drawing significant attention in solar fuel studies. Here, the authors report a stable FAPbBr 3 photoanode optimized for water oxidation to achieve a low onset potential and high applied bias photon-to-current efficiency.

Photoelectrochemical approach to solar energy conversion demands a kinetic optimization of various light-induced electron transfer processes. Of great importance are the redox mediator systems accomplishing the electron transfer processes at the semiconductor/electrolyte interface, therefore affecting profoundly the performance of various photoelectrochemical cells. Here, we develop a strategy—by addition of a small organic electron donor, tris(4-methoxyphenyl)amine, into state-of-art cobalt tris(bipyridine) redox electrolyte—to significantly improve the efficiency of dye-sensitized solar cells. The developed solar cells exhibit efficiency of 11.7 and 10.5%, at 0.46 and one-sun illumination, respectively, corresponding to a 26% efficiency improvement compared with the standard electrolyte. Preliminary stability tests showed the solar cell retained 90% of its initial efficiency after 250 h continuous one-sun light soaking. Detailed mechanistic studies reveal the crucial role of the electron transfer cascade processes within the new redox system. The electrolyte is an important component of dye-sensitized solar cells. Here, Hao et al . use an electron donor additive in the cobalt-based electrolyte, which speeds up the dye regeneration and slows down recombinations. The resulting devices are stable and more efficient than those without additive.

Reversible optical property changes in lead‐free perovskites have recently received great interest due to their potential applications in smart windows, sensors, data encryption, and various on‐demand devices. However, it is challenging to achieve remarkable color changes in their thin films. Here, methylamine gas (CH3NH2, MA0) induced switchable optical bleaching of bismuth (Bi)‐based perovskite films is demonstrated for the first time. By exposure to an MA0 atmosphere, the color of Cs2AgBiBr6 (CABB) films changes from yellow to transparent, and the color of Cs3Bi2I9 (CBI) films changes from dark red to transparent. More interestingly, the underlying reason is found to be the interactions between MA0 and Bi3+ with the formation of an amorphous liquefied transparent intermediate phase, which is different from that of lead‐based perovskite systems. Moreover, the generality of this approach is demonstrated with other amine gases, including ethylamine (C2H5NH2, EA0) and butylamine (CH3(CH2)3NH2, BA0), and another compound, Cs3Sb2I9, by observing a similar reversible optical bleaching phenomenon. The potential for the application of CABB and CBI films in switchable smart windows is investigated. This study provides valuable insights into the interactions between amine gases and lead‐free perovskites, opening up new possibilities for high‐efficiency optoelectronic and stimuli‐responsive applications of these emerging Bi‐based materials. Methylamine gas (MA0) induced switchable optical bleaching of lead‐free bismuth‐based halide perovskites through phase transformation is demonstrated for the first time. The color of Cs2AgBiBr6 and Cs3Bi2I9 films reversibly changes from yellow and red to transparent. MA0 molecules interact with Bi3+, transforming the colored perovskite phase into a transparent amorphous non‐perovskite phase. Subsequent recrystallization gives improved grain orientation and morphology.

The illumination direction and temperature can greatly affect the performance of dye-sensitized solar cells (DSSCs) when practical non-volatile solvents are used with bulky one-electron redox mediators such as cobalt tris(bipyridine). For higher performance, a tandem electrolyte system consisting of cobalt tris(bipyridine) with tris(4-methoxyphenyl)amine was used. Discrepancies in J–V hysteresis were investigated by using photocurrent turn-on transients, open-circuit voltage decay, and electrochemical impedance spectroscopy. The devices perform much better upon illumination form the counter electrode side and exhibit much less hysteresis and more stabilized power output as characterized by maximum power-point tracking (MPP) tracking.

In dye-sensitized solar cells (DSCs), the redox mediator is responsible for the regeneration of the oxidized dye and for the hole transport towards the cathode. Here, we introduce new copper complexes with tetradentate 6,6′-bis(4-(S)-isopropyl-2-oxazolinyl)-2,2′-bipyridine ligands, Cu(oxabpy), as redox mediators. Copper coordination complexes with a square-planar geometry show low reorganization energies and thus introduce smaller losses in photovoltage. Slow recombination kinetics of excited electrons between the TiO2 and CuII(oxabpy) species lead to an exceptionally long electron lifetime, a high Fermi level in the TiO2, and a high photovoltage of 920 mV with photocurrents of 10 mA∙cm−2 and 6.2% power conversion efficiency. Meanwhile, a large driving force remains for the dye regeneration of the Y123 dye with high efficiencies. The square-planar Cu(oxabpy) complexes yield viscous gel-like solutions. The unique charge transport characteristics are attributed to a superposition of diffusion and electronic conduction. An enhancement in charge transport performance of 70% despite the higher viscosity is observed upon comparison of Cu(oxabpy) to the previously reported Cu(tmby)2 redox electrolyte.

The authors express their sincere apologies to all readers of abovementioned article as mistakes were found upon discussion of the article with colleagues [...]

A cotton-like ZnO/SnO2 nanocomposite was grown by the carbothermal evaporation of a mixture of ZnO and SnO2 powders at 1100°C by the vapour-liquid-solid process, in which the Sn particles produced by the reduction of SnO2 act as the catalyst. Field-emission scanning electron microscope images suggest that the composites are made of microfibre-nanowire junction arrays. The structure is formed due to the fast growth of the ZnO microfibre and the subsequent epitaxial radial growth of the ZnO nanowires with Sn particles at the tips. The photovoltaic performance of the ZnO/SnO2 nanocomposite sensitized with a D35-cpdt dye was investigated. A dye-sensitized solar cell (DSSC) with a ZnO/SnO2 nanocomposite photoanode based on a cobalt electrolyte achieved a solar-to-electricity conversion efficiency of ~0.34% with a short circuit current (JSC) of 0.66 mA/cm2, an open circuit voltage (VOC) of 870 mV, and a fill factor (FF) of 59. The results show the potential of this one dimensional structure in cobalt electrolyte-based DSSCs; the further optimization which is needed to achieve higher efficiencies is also discussed.

Large datasets are now ubiquitous as technology enables higher-throughput experiments, but rarely can a research field truly benefit from the research data generated due to inconsistent formatting, undocumented storage or improper dissemination. Here we extract all the meaningful device data from peer-reviewed papers on metal-halide perovskite solar cells published so far and make them available in a database. We collect data from over 42,400 photovoltaic devices with up to 100 parameters per device. We then develop open-source and accessible procedures to analyse the data, providing examples of insights that can be gleaned from the analysis of a large dataset. The database, graphics and analysis tools are made available to the community and will continue to evolve as an open-source initiative. This approach of extensively capturing the progress of an entire field, including sorting, interactive exploration and graphical representation of the data, will be applicable to many fields in materials science, engineering and biosciences. Making large datasets findable, accessible, interoperable and reusable could accelerate technology development. Now, Jacobsson et al. present an approach to build an open-access database and analysis tool for perovskite solar cells.

Despite considerable research efforts on photoelectrochemical water splitting over the past decades, practical application faces challenges by the absence of efficient, stable, and scalable photoelectrodes. Herein, we report a metal-halide perovskite-based photoanode for photoelectrochemical water oxidation. With a planar structure using mesoporous carbon as a hole-conducting layer, the precious metal-free FAPbBr3 photovoltaic device achieves 9.2% solar-to-electrical power conversion efficiency and 1.4 V open-circuit voltage. The photovoltaic architecture successfully applies to build a monolithic photoanode with the FAPbBr3 absorber, carbon/graphite conductive protection layers, and NiFe catalyst layers for water oxidation. The photoanode delivers ultralow onset potential below 0 V versus the reversible hydrogen electrode and high applied bias photon-to-current efficiency of 8.5%. Stable operation exceeding 100 h under solar illumination by applying ultraviolet-filter protection. The photothermal investigation verifies the performance boost in perovskite photoanode by photothermal effect. This study is significant in guiding the development of photovoltaic material-based photoelectrodes for solar fuel applications.