Band 2, Heft 1

Silicon heterojunction solar cells consist of thin amorphous silicon layers deposited on crystalline silicon wafers. This design enables energy conversion efficiencies above 20% at the industrial production level. The key feature of this technology is that the metal contacts, which are highly recombination active in traditional, diffused-junction cells, are electronically separated from the absorber by insertion of a wider bandgap layer. This enables the record open-circuit voltages typically associated with heterojunction devices without the need for expensive patterning techniques. This article reviews the salient points of this technology. First, we briefly elucidate device characteristics. This is followed by a discussion of each processing step, device operation, and device stability and industrial upscaling, including the fabrication of solar cells with energy-conversion efficiencies over 21%. Finally, future trends are pointed out.

Nitrogen doped carbon materials are now playing an important role in cutting edge innovations for energy conversion and storage technologies such as supercapacitors and proton exchange membrane fuel cells as well as in catalytic applications, adsorption and CO 2 capture. The production of such materials using benign aqueous based processes, mild temperatures and renewable precursors is of great promise in addressing growing environmental concerns for cleaner power sources at a time of increasing global demand for energy. In this perspective, we show that nitrogen doped carbons prepared using sustainable processes such as “Hydrothermal Carbonisation” has advantages in many applications over the conventional carbons. We also summarize an array of synthetic strategies used to create such nitrogen doped carbons, and discuss the application of these novel materials.

The enormous technical developments and rapid changes in life patterns made in the recent decades have largely been attributed to the exploitation of contemporary forms of energy sources, i.e. fossil fuels. However, their finite availability and significantly high environmental impacts have aroused concerns and spurred research to find alternatives and more efficient ways to store energy. In particular, recent developments of batteries and fuel cells as energy storage devices have been proven to be very promising, but their poor power characteristics and cyclic stability hinder their wider applications. Conversely, conventional capacitors display a great outputting pulsed power, but disappointing energy characteristics. Electrochemical capacitors (ECs), which are also known as supercapacitors, bridge the crucial performance disparity between fuel cells or batteries with high energy capacities and the traditional capacitors capable of outputting pulsed high power. The main focus of this review is to outline the latest developments of the ECs and determine their current status in terms of energy and power characteristics. In particular, recent developments in materials including new synthesis methods, structural studies and advanced configurations of ECs are discussed. Moreover, several technical challenges to further development are identified. Based on the latest results, the potential of developing supercapatteries, whose performance is in between batteries and contemporary supercapacitors, are also discussed in this review.