Photovoltaic and optoelectronic device group

Abstract:

Nanoscience provides many strategies to construct high-performance materials and devices, including solar cells, thermoelectrics, sensors, transistors, and transparent electrodes. Bottom-up fabrication facilitates large-scale chemical synthesis without the need for patterning and etching processes that waste material and create surface defects. However, assembly and contacting procedures still require further development. Here, we demonstrate a light-induced plasmonic nanowelding technique to assemble metallic nanowires into large interconnected networks. The small gaps that form naturally at nanowire junctions enable effective light concentration and heating at the point where the wires need to be joined together. The extreme sensitivity of the heating efficiency on the junction geometry causes the welding process to self-limit when a physical connection between the wires is made. The localized nature of the heating prevents damage to low-thermal-budget substrates such as plastics and polymer solar cells. This work opens new avenues to control light, heat and mass transport at the nanoscale.

Abstract:

The research field of photovoltaics is booming due to the recognised imperative to realise a long term solutions to clean and inexpensive power generation. With this rapid growth in activity, new concepts and new directions, it is becoming more and more important to be able to effectively compare technological advances made in different research groups, and between the different competing technologies. In this article it is illustrated how challenging it can be to fairly asses the efficiency of a solar cell. Specific examples of how much of an influence a range of measurement practices can have on the estimated short-circuit photocurrents and efficiencies are shown for a number of the most commonly researched excitonic solar cell concepts. In the worst case scenario, systematic overestimations by a factor of 5 can be made. For completeness, the influence of the light source, and the correct method to properly calibrate a solar simulator and estimate the spectral mismatch factor is also described. The error in calibrating the light source is actually likely to lead to a much smaller variance than the definition of the active area of the solar cell. The undeniable implication is that it is essential for excitonic solar cells to be correctly masked to define the active area, if the measured efficiency is to bear a true resemblance of the device performance. Adoption of standard protocols across the field will enable a much better comparison between literature values of efficiency and more rapid and well directed technological advancement will occur. © 2012 The Royal Society of Chemistry.

Abstract:

Device optimization and ultrafast absorption spectroscopic investigations on the role of semiconducting polymer as hole-transport layer in solid-state dye sensitized solar cells suggest their dual role of dye-regeneration and light-antenna assisting in improved photoconversion-efficiencies.