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.本研究报道了一种合成策略，可制备得到氢终止型二维硅纳米片，其硅氧烷（siloxane，如Si-O-Si、OXSi）含量显著降低。该纳米片呈现出弱且宽化的光致发光（photoluminescence）特性，发光中心波长约为610 nm，绝对光致发光量子产率（absolute photoluminescence quantum yield）低至0.3%。对该纳米片进行可控氧化处理后，其光致发光峰蓝移至510 nm，量子产率提升一个数量级以上，达到8.5%。上述结果表明，可控氧化可调控二维硅的带隙，且此前针对该材料所报道的光致发光特性，部分源于氧化作用。