Pressure tuned photoluminescence and band gap in two-dimensional layered g-C3N4: the effect of interlayer interactions
We show that the photoluminescence (PL) emission color of few layered g-C3N4 (FL-CN) can be tuned from blue to yellow by applying pressure. It also exhibits an anomalous PL enhancement and obvious change in the light absorption at very low pressure. Further study reveals that the increase of pressure-induced intra-layer interactions affects the charge separation of photo-induced electrons and holes and thus leads to the PL enhancement. An obvious decrease in interlayer compressibility probably due to interlayer stacking transition in FL-CN has been observed at above 3 GPa, which becomes less compressible than that of graphite, accompanying with obvious PL intensity weakening and emission band broadening. The results suggest that interlayer interactions may play dominant roles on the optical properties of FL-CN, shedding new insights into our understanding on the PL engineering in g-C3N4.