CIGS Nanocrystal Inks for the Fabrication of Air Stable Thin Film Solar Cells

Thin film solar cells based on copper indium gallium diselenide (CIGS) and its alloys the most promising candidates for low cost photovoltaic. However, the widespread utilization of CIGS based solar cells has been hindered by high manufacturing cost. Recent advances in colloidal synthesis have made great progress in the development of next generation low cost solar cells. Synthesis and photovoltaic applications of various semiconductor nanoparticles have been demonstrated. Here, we have developed a facile solution synthesis of various CIGS and related nanocrystal inks. The as-synthesized CIGS nanocrystals can be easily assembled into thin films and converted into active absorber layers under mild thermal annealing conditions. After brief thermal treatment, the CIGS nanocrystals sinter into large and densely packed grains – a key characteristic of high efficiency CIGS thin film solar cells. By optimizing processing conditions, light to electricity conversion efficiency greater than 6% under AM1.5G illumination has been achieved. The results are very promising and further investigations are underway to improve device performance.