Articles in 2016

The grain boundaries in thin-film perovskite solar cells are responsible for non-radiative carrier recombination, which is deleterious for the optoelectronic performance. Son et al. show how to passivate the grain boundaries by using excess CH₃NH₃I in the precursor solution, achieving efficiencies of 20.4%.

Batteries are promising to support energy systems based on intermittent renewable energy, yet their investment attractiveness remains low. Using a techno-economic model, Stephan et al. find that returns can be increased and risks reduced if batteries are used for multiple stationary applications.

The recent drop in oil prices is having a profound impact on global energy markets, raising questions about how these markets might evolve over the long term. This study uses scenarios to assess the energy and emissions impacts of diverging oil price futures and which uncertainties they depend upon.

Soluble catalysts such as redox mediators are promising in enhancing energy efficiency of Li–O₂ batteries. Here, the authors propose a design principle for finding efficient redox mediators and demonstrate the application of such a new catalyst.

The ability of photovoltaic devices to harvest solar energy can be enhanced by tailoring the spectrum of incident light with thermophotovoltaic devices. Bierman et al. now show that one such device achieves a solar-to-electrical efficiency of 6.8%, exceeding that of the solar cell alone.

CdTe solar cells have not reached their full efficiency potential, in part because their voltages have lagged behind those of cells made from other semiconductors. Zhao et al. report monocrystalline CdTe solar cells with open-circuit voltages up to 1.1 V and conversion efficiencies up to 17%.

Power grids often fail during extreme weather events such as hurricanes, leaving millions of customers without electricity. A large-scale analysis of the operation of power grids in an extended geographical area now reveals that such events exacerbate vulnerabilities that are obscured during normal operation.

Efficient catalysts for the oxygen-evolution reaction, especially in alkaline media, are highly desired because of their application in various energy technologies. Now, a gold-supported NiCeO_x catalyst is shown to have excellent catalytic activity due to synergistic geometric and electronic effects.

There is an intensive effort in developing multi-shelled metal oxide nanostructures for lithium-ion battery applications. Now, a metal anion-adsorption mechanism, as opposed to the conventional cation adsorption on carbonaceous templates, is demonstrated in the synthesis of vanadium oxide hollow microspheres, which exhibit excellent battery performance.

Rechargeable aqueous batteries are attractive owing to their relatively low cost and safety. Here the authors report an aqueous zinc/manganese oxide battery that operates via a conversion reaction mechanism and exhibits a long-term cycling stability.

Controlling the surface of quantum dots has enabled higher efficiency in quantum dot solar cells. Now, the role of surface passivation and suppression of hydroxyl ligands in the performance and photostability of cells with an efficiency of 9.6% is unveiled.

Organic thermoelectric materials are emerging as low-cost, versatile alternatives to more established inorganic ones. Avery et al. report carbon nanotube-based materials with selected properties that exhibit enhanced thermoelectric performance.

The development of all-solid-state batteries requires fast lithium conductors. Here, the authors report a lithium compound, Li_9.54Si_1.74P_1.44S_11.7Cl_0.3, with an exceptionally high conductivity and demonstrate that all-solid-state batteries based on the compound have high power densities.

Government support for energy technology is vital, but quantifying its effects downstream is complicated. Towards this end, David Popp analyses scientific publication data resulting from public money, exploring the time lags between funding and new publications and the resulting policy implications.

Solar cells based on CdTe are a promising low-cost alternative to mainstream Si devices, but they usually produce voltages below 900 mV. Burst et al. now show that open-circuit voltages greater than 1 V can be achieved by doping the CdTe with a group V element.

Uncontrolled lithium deposition during cycling is a major concern in the development of lithium-based batteries. Here, the authors analyse the lithium nucleation pattern on various metal substrates and demonstrate that lithium can be selectively deposited in a nanoseed inside hollow carbon spheres.

Micrometre-size silicon particles are desirable battery anode materials but are even more prone to structure degradation than nanoscale particles. Here, graphene cages grown conformally around the micro-silicon particles are shown to improve their cycling stability.

The processing of high-performance organic solar cells usually requires environmentally hazardous solvents. Now, hydrocarbon-based processing is shown to achieve relatively high performance in a more environmentally friendly way.

The use of doped-silicon contacts in silicon solar cells adds cost and complexity to the fabrication process. These issues can now be circumvented by using dopant-free carrier-selective interfaces on silicon, realized by alkali metal fluorides and metal oxides.

The thermal degradation of perovskite solar cells is an obstacle to their commercialization. Now, the mechanisms for thermally induced structural and chemical changes are identified by in situ measurements in a transmission electron microscope.