Tuning the florescence color of gradient bandgap perovskite nanoplate by direct laser writing

摘要

Lead halide perovskites are widely applied in not only photovoltaics, but also on-chip light source, nanolaser, andphoton detection. In order to promote the incorporation of perovskite into integrated devices, microscale colorpatterning flexibility is a very important step. Femtosecond (fs) laser fabrication has shown significant advantagesof high spatial resolution, low surround damage, and high processing efficiency over the other laser fabrication.Compared to the state-of-art techniques, the straightforward fs-direct laser writing (fs-DLW) also has advantagesof mask-free, simple one step, and contactless. Here, a specially designed formamidinium lead mixed-halidenanoplatelet (FAPb(Br_xI_(1-x))_3 NP) with gradient bandgap is fabricated by chemical vapor deposition method. Then,spatially resolved modulation of the fluorescence by fs-DLW is demonstrated on the as-grown NP. Thefluorescence color is modulated from red to green under a controlled laser pulse, due to the replacement of iodideions by bromide ions. Specifically, the as-grown NP (thickness≈800 nm) is with a gradual bromide-iodidecomposition along the depth, mainly exhibits an emission of 710-nm from the bottom iodine rich phase. Afterhalide substitution induced by fs-DLW, new fluorescence peaks appear in the wavelength range of 540 to 700 nm,which is controlled by the fs-DLW conditions. The fluorescent color is spatially modulated from red to green,enabling microscale resolved multicolor emission, implying the potential applications in micro-encryption,sensors, multicolor displays, lasers, and light-emitting devices.