Dr. Bo Tan, Associate Professor, Ryerson University, Canada.

Speech Title: Laser synthesis nanomaterial for full spectrum light absorption

Abstract: Femtosecond laser, due to its extreme high peak power, demonstrates unique characteristics in nanomaterial synthesis. Using femtosecond laser of MHz frequency pulses, we created nanoscale titanium oxides or silicon by ablation of solid targets. The created nanostructured material showed significant improvement of the photon absorption capacity in a wide range of spectrum, 400nm-1100nm. The titanium oxides especially exhibited a substantial and steady absorption capability in the NIR range of 750-1000 nm, while the nanostructured silicon shows strongest absorption at 400nm. A prototype solar cell was fabricated by embedding nanostructured silicon as a depletion region in the p-n junction. The power conversion efficiency was measured as 12%. The full spectrum absorption can be attributed to several characteristics of the nanomaterial, including the multi-phase, polycrystalline, high density of defects and quantum size.