Access to clean, affordable and reliable energy has been a cornerstone of the world's increasing prosperity and economic growth since the beginning of the industrial revolution. Our use of energy in the twenty–first century must also be sustainable. Solar and water–based energy generation, and engineering of microbes to produce biofuels are a few examples of the alternatives. This Perspective puts these opportunities into a larger context by relating them to a number of aspects in the transportation and electricity generation sectors. It also provides a snapshot of the current energy landscape and discusses several research and development opportunities and pathways that could lead to a prosperous, sustainable and secure energy future for the world.

Opportunities and challenges for a sustainable energy future

Graphene and monolayer transition metal dichalcogenides (TMDs) are promising materials for next-generation ultrathin optoelectronic devices. Although visually transparent, graphene is an excellent sunlight absorber, achieving 2.3% visible light absorbance in just 3.3 A thickness. TMD monolayers also hold potential as sunlight absorbers, and may enable ultrathin photovoltaic (PV) devices due to their semiconducting character. In this work, we show that the three TMD monolayers MoS2, MoSe2, and WS2 can absorb up to 5–10% incident sunlight in a thickness of less than 1 nm, thus achieving 1 order of magnitude higher sunlight absorption than GaAs and Si. We further study PV devices based on just two stacked monolayers: (1) a Schottky barrier solar cell between MoS2 and graphene and (2) an excitonic solar cell based on a MoS2/WS2 bilayer. We demonstrate that such 1 nm thick active layers can attain power conversion efficiencies of up to ∼1%, corresponding to approximately 1–3 orders of magnitude higher power de...

Extraordinary Sunlight Absorption and One Nanometer Thick Photovoltaics Using Two-Dimensional Monolayer Materials

Over the past decade, electrochemical energy storage (EES) devices have greatly improved, as a wide variety of advanced electrode active materials and new device architectures have been developed. These new materials and devices should be evaluated against clear and rigorous metrics, primarily based on the evidence of real performances. A series of criteria are commonly used to characterize and report performance of EES systems in the literature. However, as advanced EES systems are becoming more and more sophisticated, the methodologies to reliably evaluate the performance of the electrode active materials and EES devices need to be refined to realize the true promise as well as the limitations of these fast-moving technologies, and target areas for further development. In the absence of a commonly accepted core group of metrics, inconsistencies may arise between the values attributed to the materials or devices and their real performances. Herein, we provide an overview of the energy storage devices from conventional capacitors to supercapacitors to hybrid systems and ultimately to batteries. The metrics for evaluation of energy storage systems are described, although the focus is kept on capacitive and hybrid energy storage systems. In addition, we discuss the challenges that still need to be addressed for establishing more sophisticated criteria for evaluating EES systems. We hope this effort will foster ongoing dialog and promote greater understanding of these metrics to develop an international protocol for accurate assessment of EES systems.

Towards establishing standard performance metrics for batteries, supercapacitors and beyond.

CH3NH3PbI3-based solar cells were characterized with electron beam-induced current (EBIC), and compared to CH3NH3PbI3-xClx ones. A spatial map of charge separation efficiency in working cells shows p-i-n structures for both thin film cells. Effective diffusion lengths, LD, (from EBIC profile) show that holes are extracted significantly more efficiently than electrons in CH3NH3PbI3, explaining why CH3NH3PbI3-based cells require mesoporous electron conductors, while CH3NH3PbI3-xClx ones, where LD values are comparable for both charge types, do not.

Why Lead Methylammonium tri-IODIDE perovskite-based solar cells requires a mesoporous electron transporting scaffold (but not necessarily a hole conductor)

Developments in organic-inorganic lead halide-based perovskite solar cells have been meteoric over the last 2 years, with small-area efficiencies surpassing 15%. We address the fundamental issue of how these cells work by applying a scanning electron microscopy-based technique to cell cross-sections. By mapping the variation in efficiency of charge separation and collection in the cross-sections, we show the presence of two prime high efficiency locations, one at/near the absorber/hole-blocking-layer, and the second at/near the absorber/electron-blocking-layer interfaces, with the former more pronounced. This 'twin-peaks' profile is characteristic of a p-i-n solar cell, with a layer of low-doped, high electronic quality semiconductor, between a p- and an n-layer. If the electron blocker is replaced by a gold contact, only a heterojunction at the absorber/hole-blocking interface remains.

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Elucidating the charge carrier separation and working mechanism of CH 3 NH 3 PbI 3− x Cl x perovskite solar cells

Fundamentals of materials for energy and environmental sustainability

VOLUME I: SUPERCONDUCTIVITY, MATERIALS AND PROCESSES Fundamentals of Superconductivity Introduction to superconductivity and superconducting materials Characteristic properties Elementary theory Critical currents of type II superconductors Processing Introduction to processing methods Bulk materials Wires and tapes Thick and thin films Superconductor contacts High Temperature Superconductors YBCO BSCCO TIBCCO Mercury superconductors Magnesium diboride VOLUME II: CHARACTERIZATION, APPLICATION AND CRYOGENICS Characterization Techniques Structure/microstructure Measurement and interpretation of electromagnetic properties Measurement of physical properties Applications High current applications Trapped flux devices High frequency devices Josephson junction devices Other devices Introduction to Refrigeration Methods Emerging Materials Chevrel phases Unconventional superconductivity in heavy fermion and ruthenate superconductors Organic superconductors Fullerene superconductors Future high Tc superconductors Appendices Manufacturer and supplier directory Hazards: environment and safety Teach yourself phase diagrams

Handbook of superconducting materials

There has been considerable progress in the development of thin-film photovoltaic devices with new efficiency records and enhanced durability. These achievements are the result of significant advances in the fundamental understanding of the materials, interfaces and devices. With 18 countries represented, this truly international volume brings together engineers and researchers from academic, industrial and national laboratories worldwide to review different materials systems and address common issues and problems. A wide variety of topics related to the development of thin-film photovoltaic and related devices, including thick-film transistors and materials for flat-panel displays, are addressed. Areas of emphasis include materials synthesis, device fabrication and characterization, and modelling. Topics include: thin-film amorphous silicon devices; thin-film silicon devices; thin-film devices based on copper-indium diselenide; cadmium-telluride devices; transparent conductive oxides and related materials for thin-film devices; and novel concepts for thin-film photovoltaics.

Thin films for photovoltaic and related device applications

The electrical and structural properties of sputtered indium oxide (In 2 O 3 ) thin films doped with Mo, Zr, and Ti were studied. Properties of these films are compared to undoped In 2 O 3 and tin-doped In 2 O 3 (ITO). The as-sputtered films, doped with Mo (IO:Mo), exhibited high mobility (45 cm 2 V -1 s -1 ). Pulsed laser deposition (PLD) was also used to deposit IO:Mo films. The highest mobility achieved for an as-deposited PLD IO:Mo film deposited onto a glass substrate was 42.7 cm 2 V -1 s -1 . However, PLD IO:Mo films deposited on single-crystal yttria-stabilized zirconia (YSZ) substrates exhibited a higher mobility of 53.6 cm 2 V -1 s -1 and a greater degree of structural orientation than the sputtered films. Following post-deposition annealing, both the sputtered films on glass, and the PLD films on YSZ, exhibited improved mobilities of 47 and 66 cm 2 V -1 s -1 , respectively.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400155836

Thin-Film Indium Oxide Doped with Refractory Metals

This work aims to offer a definitive collection of material describing techniques for the fabrication and analysis of superconducting materials. Its four main sections cover the fundamentals of superconductivity, processing, characterization techniques and materials.

DS Ginley

Papers

Fundamentals of materials for energy and environmental sustainability

Handbook of superconducting materials

Thin films for photovoltaic and related device applications

Thin-Film Indium Oxide Doped with Refractory Metals

Superconductivity, materials and processes