US scientists first detect solar cells with nanometer accuracy

The National Institute of Technology and Technology (NIST) recently released a news report that the agency's researchers used two new technologies to detect the changes in chemical composition and defects of widely used solar cells for the first time with nano-level accuracy. New technologies have detected common solar cells made from cadmium telluride semiconductor materials, which are expected to help scientists better understand the microstructure of solar cells and may suggest ways to further increase the efficiency of solar photovoltaic conversion.

In the research, NIST scientists used two auxiliary methods relying on atomic force microscopy (AFM) to measure the amount of light absorbed by a wide range of wavelengths from visible light to mid-infrared light in solar cell samples by light-induced resonance (PTIR), thus at the nanoscale scale. The composition of the solar cell and its defects were obtained. Another technique, called scanning near-field optical microscopy (dt-NSOM), captures the changes in solar cell composition and defects by recording the amount of light transmitted at a particular location, resulting in a detailed nanoscale image.

Experiments have shown that the defects in the crystal arrangement of the material are related to the impurities in its chemical composition. The new technology can detect the spatial variation of the so-called deep defects in the cadmium telluride samples. These defects cause recombination of cadmium telluride with electrons and protons (positively charged particles) in other semiconductors rather than power generation, which is one of the key reasons why solar cells cannot achieve theoretical results.

The research results have wide applicability and will contribute to solar cell research and better understanding of various photovoltaic materials. The research was published in the Nanoscale magazine on April 12, 2017.

June 28, 2017 Source: Ministry of Science official website