Mr. Chin-Yi Liu, a graduate student working in Professor Kortshagen’s group, demonstrated the first hybrid solar cell based on silicon nanocrystals and a conductive polymer, poly-3(hexylthiophene) (P3HT). The solar cell utilizes a blend of silicon nanocrystals between 3-10 nm in diameter and the organic semiconductor P3HT. Solar radiation is absorbed either by the polymer or by the silicon nanocrystals and produces an excited electron which is bound to the so-called hole, a missing electron left behind by the excitation process. In Mr. Liu’s solar cell, such electron-hole pairs are separated, as electrons tend to transfer to the silicon crystals while holes transfer to the polymer. After being separated, both types of charge carriers then travel to their respective electrodes either in the network of abutted silicon nanocrystals or in the polymer, which produces a useable current. Hybrid organic-inorganic solar cells such as Mr. Liu’s are intensely studied since they have the potential for ultra-low cost manufacturing. While the concept is not new, Mr. Liu’s research is the first that demonstrates the use of abundant, non-toxic and environmentally benign silicon nanocrystals.
