Cheap high quality solar cells use nanopillars

A new type of solar cell module based on the matrix of nano columns was created by US researchers.

According to the inventors, this module is very flexible, high-performance, and can be fabricated by industrial-scale processing techniques - which means it can provide a new way to create panels. Quality and cheap solar batteries.

Ali Javey and colleagues at the University of California, Berkeley developed the Cadmium Sulphide nanotubes matrix (CdS) on anode aluminum oxide films. These columns are very uniform cylinders with a single crystal structure with a diameter of 200 nm and a height of 500 nm. To create the pillars, the group deposited a thin film of gold in highly homogeneous pores created from aluminum chips after being anode. This golden layer will serve as the nucleation layer for nanopillars in the VLS (Vapor - Liquid - Solid) process - a gas-liquid-solid phase process, a technique that creates an orderly structure with adjustable orientation. control.

Cadmium Sulphide (CdS) is a semiconductor and nano columns (nanopillar) will act as photovoltaic cells, allowing the conversion of light energy into electrical current. Previous studies have shown that such a structure will have a higher efficiency than a plane structure because more photons are absorbed at a greater depth in the aurora electricity.

Figure 1 .SEM images (a, b) of nanopillars and HRTEM images show the single crystal structure of nanopillar (c).Below is a very flexible solar cell structure (Nature Materials - July 5, 2009).

The photovoltaic cells of the group created in the structure of nanopillars have a conversion efficiency of about 6%, higher than other thin, and flexible components , including components that use structured materials. nano. Another strong point compared to block solar cell modules that a small amount of active semiconductor materials need to be used in components, allowing a significant reduction in the cost of components - according to Javey. The fabrication technique used by the team also promises to commercialize the product because it is compatible with ' roll-to-roll ' processing - a common technique for making electronic components.

' The nanopillars we produce can be used to develop practical technologies for low-cost and low-light photovoltaic batteries with a very good performance ' - Javey said - ' Our research can lead to important links to large-scale integration technologies of solar cell modules for a wide range of applications. There are still many challenges ahead of us, but research results have shown the potential of technology. '

Figure 2 .A photo of a solar cell module on a glass base (a);characteristic IV (b) under different light intensities;short-circuit current (c) Js-c indicates linear dependence on light intensity, while coefficient fills FF, decreases when intensity increases;open-circuit voltage (d) VOC increases with intensity and energy conversion efficiency is almost independent of the light intensity (P = 17 ~ 100 mW cm-2 (Nature Materials - July 5, 2009).

The research team, including researchers from Lawrence Berkeley National Laboratory, is currently developing plans to enhance the photoelectric conversion efficiency in this device.

The first thing they can do is optimize, or replace the top contact material, which currently consumes up to 50% of optical transmission. ' We will also have to study more materials for the component structure and how to build it, and will try to create more practical technology for large-scale integration techniques ' - Javey added. .

Currently, the immediate objective is to replace CdS material because of its toxicity.

Can see details of these results in the article just published in Nature Materials - July 5, 2009 .