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| Open AccessBimolecular recombination in methylammonium lead triiodide perovskite is an inverse absorption process
Radiative bimolecular processes will dominate charge-carrier recombination in hybrid perovskite solar cells operating near the Shockley-Queisser limit. Here, the authors show that such processes are the inverse of absorption and increase as distribution functions sharpen towards lower temperatures.
- Christopher L. Davies
- , Marina R. Filip
- & Laura M. Herz
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Article
| Open AccessCarbon-doped SnS2 nanostructure as a high-efficiency solar fuel catalyst under visible light
Photocatalytic reduction of CO2 to hydrocarbons is a promising route to both CO2 utilization and renewable fuel production. Here the authors identify that carbon-doped SnS2 possesses a high catalytic efficiency towards CO2 reduction owing to low photogenerated charge recombination rates.
- Indrajit Shown
- , Satyanarayana Samireddi
- & Kuei-Hsien Chen
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Article
| Open AccessLight-tuned selective photosynthesis of azo- and azoxy-aromatics using graphitic C3N4
The synthesis of azo- and azoxy-aromatic dyes via photoreduction of nitroaromatics is hindered by high costs and low catalytic efficiencies and selectivities. Here the authors demonstrate the facile synthesis of these important dyes from their corresponding nitroaromatic precursors by using an inexpensive graphitic C3N4 photocatalyst.
- Yitao Dai
- , Chao Li
- & Ren Su
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Article
| Open AccessThin single crystal perovskite solar cells to harvest below-bandgap light absorption
Thin films of halide perovskites are promising for solar cell technology but they do not perform well at the band edge due to the low optical absorption. Herein, Chen et al. fabricate a high efficiency single crystal perovskite solar cell with thicker single crystals to harvest the below-bandgap photons.
- Zhaolai Chen
- , Qingfeng Dong
- & Jinsong Huang
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| Open AccessA Co3O4-CDots-C3N4 three component electrocatalyst design concept for efficient and tunable CO2 reduction to syngas
Simultaneous electrochemical reduction of CO2 and H+/H2O is an attractive renewable route to produce syngas mixtures. Here, the authors introduce a ternary Co3O4-CDots-C3N4 electrocatalyst that couples hydrogen evolution and CO2 reduction catalysts and achieves cheap, stable and tunable production of syngas.
- Sijie Guo
- , Siqi Zhao
- & Zhenhui Kang
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Article
| Open AccessSpectroscopic detection of halogen bonding resolves dye regeneration in the dye-sensitized solar cell
Dye-sensitized solar cells rely on molecular dyes to absorb light and conduct electrons. Parlane et al. show that weak forces such as hydrogen bonding can be responsible for the dye regeneration step of solar cells and have an impact on the photovoltage and the efficiency.
- Fraser G. L. Parlane
- , Chantal Mustoe
- & Curtis P. Berlinguette
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| Open AccessUltrafast bridge planarization in donor-π-acceptor copolymers drives intramolecular charge transfer
Tracking and understanding charge transfer process is central yet challenging to designing efficient organic photovoltaics. Roy et al. monitor real-time structural changes in donor-π-acceptor polymer backbone, and enumerate the role of π-bridge torsions during intramolecular charge transfer.
- Palas Roy
- , Ajay Jha
- & Jyotishman Dasgupta
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| Open AccessOptically-controlled long-term storage and release of thermal energy in phase-change materials
Phase-change materials offer excellent thermal storage due to their high latent heat; however, they suffer from spontaneous heat loss. Han et al., use organic photo-switching dopants to introduce an activation energy barrier which enables controllable thermal energy release and retention.
- Grace G. D. Han
- , Huashan Li
- & Jeffrey C. Grossman
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Article
| Open AccessUnderstanding activity and selectivity of metal-nitrogen-doped carbon catalysts for electrochemical reduction of CO2
Inexpensive and selective electrocatalysts for CO2 reduction hold promise for sustainable fuel production. Here, the authors report N-coordinated, non-noble metal-doped porous carbons as efficient and selective electrocatalysts for CO2 to CO conversion.
- Wen Ju
- , Alexander Bagger
- & Peter Strasser
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Article
| Open AccessPotential for natural evaporation as a reliable renewable energy resource
The evaporation of water represents an alternative source of renewable energy. Building on previous models of evaporation, Cavusoglu et al. show that the power available from this natural resource is comparable to wind and solar power, yet it does not suffer as much from varying weather conditions.
- Ahmet-Hamdi Cavusoglu
- , Xi Chen
- & Ozgur Sahin
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| Open AccessUltrathin high band gap solar cells with improved efficiencies from the world’s oldest photovoltaic material
Wide band gap semiconductors are important for the development of tandem photovoltaics. By introducing buffer layers at the front and rear side of solar cells based on selenium; Todorov et al., reduce interface recombination losses to achieve photoconversion efficiencies of 6.5%.
- Teodor K. Todorov
- , Saurabh Singh
- & Richard Haight
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| Open AccessDipole-field-assisted charge extraction in metal-perovskite-metal back-contact solar cells
Simplified device concepts may become important for the development of low cost photovoltaics. Lin et al. report solar cells based on interdigitated gold back-contacts and metal halide perovskites where charge extraction is assisted via a dipole field generated by self-assembled molecular monolayers.
- Xiongfeng Lin
- , Askhat N. Jumabekov
- & Udo Bach
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| Open AccessConsolidation of the optoelectronic properties of CH3NH3PbBr3 perovskite single crystals
Metal halide perovskites for optoelectronic devices have been extensively studied in two forms: single-crystals or polycrystalline thin films. Using spectroscopic approaches, Wenger et al. show that polycrystalline thin films possess similar optoelectronic properties to single crystals.
- Bernard Wenger
- , Pabitra K. Nayak
- & Henry J. Snaith
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Article
| Open AccessAntisite occupation induced single anionic redox chemistry and structural stabilization of layered sodium chromium sulfide
The rational design of intercalation electrodes is largely confined to the optimization of redox chemistry of transition metals and oxygen. Here, the authors report the single anionic redox process in NaCrS2 where it is sulfur rather than chromium that works as the electrochemical active species.
- Zulipiya Shadike
- , Yong-Ning Zhou
- & Zheng-Wen Fu
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Article
| Open AccessLow carbon renewable natural gas production from coalbeds and implications for carbon capture and storage
Coalbeds produce natural gas, which has been observed to be enhanced by in situ microbes. Here, the authors add plant-derived carbohydrates (monosaccharides) to coal seams to be converted by indigenous microbes into natural gas, thus demonstrating a potential low carbon renewable natural gas resource.
- Zaixing Huang
- , Christine Sednek
- & Shengpin Li
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| Open AccessUltrafast carrier thermalization in lead iodide perovskite probed with two-dimensional electronic spectroscopy
Carrier-carrier scattering rates determine the fundamental limits of carrier transport and electronic coherence. Using two-dimensional electronic spectroscopy with sub-10 fs resolution, Richter and Branchi et al. extract carrier thermalization times of 10 to 85 fs in hybrid perovskites.
- Johannes M. Richter
- , Federico Branchi
- & Felix Deschler
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| Open AccessImpact of interfacial molecular orientation on radiative recombination and charge generation efficiency
Molecular orientation profoundly affects the performance of donor-acceptor heterojunctions, whilst it has remained challenging to investigate the detail. Using a controllable interface, Ran et al. show that the edge-on geometries improve charge generation at the cost of non-radiative recombination loss.
- Niva A. Ran
- , Steffen Roland
- & Thuc-Quyen Nguyen
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Article
| Open AccessDiffusion engineering of ions and charge carriers for stable efficient perovskite solar cells
Ion migration in perovskite solar cells are known to cause hysteresis and instability. Biet al., report a charge extraction layer based on graphene, fullerenes and carbon quantum dots which suppresses ion diffusion and enhances charge carrier diffusion leading to efficient devices with improved stability.
- Enbing Bi
- , Han Chen
- & Liyuan Han
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| Open Access11% efficiency solid-state dye-sensitized solar cells with copper(II/I) hole transport materials
Inadequate pore infiltration and low conductivity of hole transporter materials limit the performance of solid-state dye-sensitized solar cells. Using fast charge-exchange Cu(II/I) complexes as part of the hole transporting material, Caoet al. overcome these issues to achieve a record photoconversion efficiency of 11%.
- Yiming Cao
- , Yasemin Saygili
- & Michael Grätzel
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| Open AccessElectrochemical generation of sulfur vacancies in the basal plane of MoS2 for hydrogen evolution
In order to fully utilize sulfur vacancies in MoS2 catalysts for industrial applications, a facile and general route for making sulfur vacancies in MoS2 is needed. Here, the authors introduce a scalable route towards generating sulfur vacancies on the MoS2basal plane using electrochemical desulfurization.
- Charlie Tsai
- , Hong Li
- & Frank Abild-Pedersen
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Article
| Open AccessTwo-step photon up-conversion solar cells
Harvesting incident photons with energy below the bandgap may lead to highly efficient solar cells. By introducing InAs quantum dots at the hetero-interface, Asahiet al. achieve efficient two step photon up-conversion resulting in additional photocurrent and very high external quantum efficiency.
- Shigeo Asahi
- , Haruyuki Teranishi
- & Takashi Kita
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| Open AccessSynergy of ammonium chloride and moisture on perovskite crystallization for efficient printable mesoscopic solar cells
The commercialization of solar cells based on hybrid perovskites requires challenges of device stability and scalable production to be addressed. Ronget al. report ambient-processed printable mesoscopic perovskite solar cells with a lifetime of over 130 days in ambient air with 30% relative humidity.
- Yaoguang Rong
- , Xiaomeng Hou
- & Hongwei Han
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Article
| Open AccessSelf-surface charge exfoliation and electrostatically coordinated 2D hetero-layered hybrids
Synthesis of atomically thin 2D hetero-layered structures remains a challenge. Here, the authors report a scalable approach to fabricating 2D hetero-layered metal chalcogenides of various compositions: self-surface charge exfoliation, followed by electrostatic coupling.
- Min-Quan Yang
- , Yi-Jun Xu
- & Ghim Wei Ho
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| Open AccessAcoustic-optical phonon up-conversion and hot-phonon bottleneck in lead-halide perovskites
Slow cooling of hot charge carriers in lead halide perovskite could be used in photovoltaics devices. Here, Yanget al. study hot carrier dynamics by transient absorption spectroscopy. They relate the phonon bottleneck to the up-conversion of low-energy phonons, facilitated by the presence of organic cations.
- Jianfeng Yang
- , Xiaoming Wen
- & Gavin Conibeer
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Article
| Open AccessThermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD
Processing is crucial to ensure material quality and stability in perovskite solar cells. Here, Poolet al. develop a scalable infrared annealing method and use in situXRD to map the processing phase space relative to the device efficiency. This provides a tool to determine processing requirements.
- Vanessa L. Pool
- , Benjia Dou
- & Michael F. Toney
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| Open AccessLong-term efficient organic photovoltaics based on quaternary bulk heterojunctions
Organic photovoltaics suffer from degradation. Here, Namet al. develop a quaternary blend and fabricate devices which lose 28% of their initial efficiency after one year of operation at 65 °C.
- Minwoo Nam
- , Minjeong Cha
- & Doo-Hyun Ko
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Article
| Open AccessTi3C2 MXene co-catalyst on metal sulfide photo-absorbers for enhanced visible-light photocatalytic hydrogen production
Solar hydrogen production through photocatalytic water splitting requires active and stable co-catalysts to replace platinum. Here, the authors use DFT to identify Ti3C2nanoparticles as potential co-catalysts, and assess their photocatalytic hydrogen production activity.
- Jingrun Ran
- , Guoping Gao
- & Shi-Zhang Qiao
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| Open AccessFluorination-enabled optimal morphology leads to over 11% efficiency for inverted small-molecule organic solar cells
Organic solar cells based on solution-processable small molecules still lag behind their macromolecule counterparts. Here, Denget al. develop molecular donors to pair with PC71BM and study how the degree of fluorination impacts the morphology of the heterojunction and the efficiency of the devices.
- Dan Deng
- , Yajie Zhang
- & Zhixiang Wei
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Article
| Open AccessRadiative cooling to deep sub-freezing temperatures through a 24-h day–night cycle
Radiative cooling relies on the atmosphere’s transparency window. Here the authors achieve up to 42 °C drops in temperature for low thermal loads under diffuse sunlight by improving the selectivity of the emissivity and the thermal management of their devices.
- Zhen Chen
- , Linxiao Zhu
- & Shanhui Fan
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| Open AccessCo-axial heterostructures integrating palladium/titanium dioxide with carbon nanotubes for efficient electrocatalytic hydrogen evolution
Hydrogen evolution by water electrolysis is a promising route to 'green energy', but efficiency is still an issue. Here, the authors make mixed organic/inorganic hierarchical nanostructures with high hydrogen evolution activity, identifying synergic effects in the material contributing to enhanced efficiency.
- Giovanni Valenti
- , Alessandro Boni
- & Francesco Paolucci
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| Open AccessRe-assessment of net energy production and greenhouse gas emissions avoidance after 40 years of photovoltaics development
While the photovoltaic industry aims to achieve cleaner energy production, it consumes energy and emits greenhouse gases during production and deployment. Here, Louwenet al. show that the industry has likely already reached break-even points for both greenhouse gases emissions and electricity consumption.
- Atse Louwen
- , Wilfried G. J. H. M. van Sark
- & Ruud E. I. Schropp
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| Open AccessEfficiency limits for photoelectrochemical water-splitting
Theoretical limiting efficiencies play a critical role in determining technological viability and expectations for device prototypes. Here, the authors present a unified framework for photoelectrochemical device performance through which previous limiting efficiencies can be understood and contextualized.
- Katherine T. Fountaine
- , Hans Joachim Lewerenz
- & Harry A. Atwater
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| Open AccessTrapped charge-driven degradation of perovskite solar cells
Improving the stability of perovskite solar cells remains crucial. Here, Ahn et al. show that trapped charges at grain boundaries induce the dissociation of the perovskite compound in the presence of moisture, and explain why degradation is irreversible under illumination and reversible in the dark.
- Namyoung Ahn
- , Kwisung Kwak
- & Mansoo Choi
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| Open AccessSolar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30%
In order to be practical for large-scale deployment, the cost of solar hydrogen generation must be significantly reduced. Here, the authors employ a triple-junction solar cell with two series connected polymer electrolyte membrane electrolysers to achieve solar to hydrogen efficiency of 30%.
- Jieyang Jia
- , Linsey C. Seitz
- & Thomas F. Jaramillo
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| Open AccessDonor polymer design enables efficient non-fullerene organic solar cells
In organic photovoltaics, electron acceptors are developed to replace fullerenes, and new donors need to be designed to match these acceptors. Here, the authors show that a polymer with strong temperature dependent aggregation and intentionally reduced crystallinity matches non-fullerene acceptors.
- Zhengke Li
- , Kui Jiang
- & He Yan
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Article
| Open AccessIn-depth analysis of chloride treatments for thin-film CdTe solar cells
High performance CdTe thin film solar cells typically require a chloride activation treatment. Here, Majoret al. show that the main effect of the most effective chloride-based treatments is chloride accumulation at grain boundaries and that it results in improved open circuit voltages.
- J. D. Major
- , M. Al Turkestani
- & K. Durose
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Article
| Open AccessThermally enhanced photoluminescence for heat harvesting in photovoltaics
In photovoltaics, sub-band gap energy photons can be harvested using up-conversion strategies. Here, the authors show that the thermally enhanced up-converted photoluminescence results in enhanced energy conversion, for an accessible temperature range and with a broad range of incident photon energy.
- Assaf Manor
- , Nimrod Kruger
- & Carmel Rotschild
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Article
| Open AccessTheory of highly efficient multiexciton generation in type-II nanorods
Multiple exciton generation could help limit thermalization losses in solar cells, but the efficiency of the process is still limited. Here, the authors show by atomistic calculations that type-II interfaces in nanostructures along with a change in exciton cooling rate favour multiple exciton generation.
- Hagai Eshet
- , Roi Baer
- & Eran Rabani
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Article
| Open AccessEnhancing stability and efficiency of perovskite solar cells with crosslinkable silane-functionalized and doped fullerene
Perovskite solar cells reach high efficiencies but their stability remains a challenge. Here, Bai et al. functionalize the fullerene-based transport layer with hydrophobic and crosslinkable molecules to prepare devices reaching 19% efficiency and degrading by 10% over a month in ambient conditions.
- Yang Bai
- , Qingfeng Dong
- & Jinsong Huang
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Article
| Open AccessUpscaling of integrated photoelectrochemical water-splitting devices to large areas
The realization of photoelectrochemical water splitting requires the upscale of associated technologies. Here, the authors report a scalable design based on independent photovoltaic and electrochemical silicon thin-film modules and assess its solar hydrogen generation performance.
- Bugra Turan
- , Jan-Philipp Becker
- & Stefan Haas
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Article
| Open AccessThe fate of electron–hole pairs in polymer:fullerene blends for organic photovoltaics
Charge generation and transport are crucial to the performance of organic solar cells, but the mechanism remains controversial. Causa’ et al. show that the phase morphology of polymer:fullerene blends determines the exciton dissociation at femtoseconds, although the spatial separation can occur at picoseconds.
- Martina Causa'
- , Jelissa De Jonghe-Risse
- & Natalie Banerji
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Article
| Open AccessHybrid bio-photo-electro-chemical cells for solar water splitting
Photoelectrochemical water splitting uses solar power to decompose water to hydrogen and oxygen. Here, the authors integrate thylakoid membranes extracted from spinach into a bio-photo-electro-chemical cell capable of overall water splitting without the need for any sacrificial reagents.
- Roy I. Pinhassi
- , Dan Kallmann
- & Avner Rothschild
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Article
| Open AccessStructural and compositional dependence of the CdTexSe1−x alloy layer photoactivity in CdTe-based solar cells
Using a CdTexSe1−x alloy in CdTe solar cells leads to better performances. Here, Poplawsky et al. show that the photoactive properties of the alloy depend on its chemical composition and structural properties, and derive a phase diagram to further optimize alloy growth for photovoltaic devices.
- Jonathan D. Poplawsky
- , Wei Guo
- & Yanfa Yan
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Article
| Open AccessSeparating hydrogen and oxygen evolution in alkaline water electrolysis using nickel hydroxide
Alkaline water electrolyzers are promising devices for hydrogen generation, although hydrogen/oxygen mixing can be problematic. Here, the authors use nickel hydroxide as a redox mediator to decouple the hydrogen and oxygen production, overcoming the gas-mixing issue.
- Long Chen
- , Xiaoli Dong
- & Yongyao Xia
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Article
| Open AccessElectrochemical polymerization of pyrene derivatives on functionalized carbon nanotubes for pseudocapacitive electrodes
Electrochemically active organic molecules are an important class of electrode materials for energy storage. Here, the authors report organic electrodes made of polycyclic aromatic hydrocarbons and functionalized few-walled carbon nanotubes, which show promising electrochemical performance.
- John C. Bachman
- , Reza Kavian
- & Seung Woo Lee