An EU parliamentary directive mandates that 20 % of the energy consumed within the EU must be renewable by the year 2020. To support this objective, there is an urgent need to reinforce scientific efforts in the field of renewable energy. In the search for high-performance, low-cost solar cells, colloidal semiconducting nanocrystals are at the forefront. These nano-sized crystalline particles are electrically conductive and have various properties that make them unusual and promising for application in solar cells. These properties include that their energy absorption is controllable, they have strong absorption potential and they are stable in response to light. However, many state-of-the-art nanocrystal systems intended for use in photovoltaic cells are based on toxic materials or scarce elements. It is important for scientists to develop new systems based on environmentally benign and abundant elements with strong absorption properties. The EU-funded SUNLIGHT (Solution-processed nanocrystal photovoltaics from environmentally benign and earth-abundant elements) initiative optimised the synthesis of two novel colloidal semiconducting nanocrystal candidates and developed their application in photovoltaic cells. Project researchers did this by first identifying a few potential candidates for the nanocrystal systems. They chose the candidates for their low raw material costs, their high absorption coefficients and other relevant properties. The scientists then developed ways to synthesise two of these candidate materials and optimised their application in photovoltaic cells. They chose the two nanocrystal systems to focus on based on the results of the synthesis research and device performance. The physical and chemical properties of semiconductor nanocrystals depend on their composition, shape, structure and surface chemistry. Therefore, SUNLIGHT researchers investigated the effect of such variables on the semiconductor nanocrystal properties. By developing solar cells based on these new nanocrystals, this initiative has gained a fundamental understanding of different colloidal semiconducting nanocrystals. It also helps to explain how surface properties can impact the application of semiconductor nanocrystals in photovoltaic cells. SUNLIGHT results offer new research methods for improving the performance of solar cells by applying environmentally benign colloidal nanocrystals.
Solar cells, colloidal semiconducting nanocrystal, solar energy, photovoltaic cells, SUNLIGHT