Elucidating the Role of Oxidation in Two-dimensional Silicon Nanosheets

We report a synthetic protocol that yields hydrogen-terminated 2D silicon nanosheets with greatly reduced siloxane (e.g., Si-O-Si, OXSi) content. These nanosheets displayed weak, broad photoluminescence centered near 610 nm with an absolute photoluminescence quantum yield as low as 0.3%. Intentional oxidization of the nanosheets blueshifted the photoluminescence peak to 510 nm and increased the quantum yield by more than an order of magnitude to 8.5%. These results show that controlled oxidation modulates the bandgap of 2D silicon and that previously reported photoluminescence properties for this material resulted, in part, from oxidation.