## 3 Results and Discussion
The peak at 1125 cm\({}^{-1}\) originated from the vibration absorption of the -Si-O-Si- group, owing to the hydrolysis condensation between the -Si-OH groups or the -Si-OH and -SiOC\({}_{2}\)H\({}_{5}\) groups [37]. Therefore, the mechanism of CsPbBr\({}_{3}\) nanocrystals with APTES can be summarized as follows: the polar -NH\({}_{2}\) group of APTES closely connects to CsPbBr\({}_{3}\) nanocrystals and three ethoxyl siloxane groups hydrolyze to form -Si-OH, following a dehydration process between the -SiOH groups or -SiOH and -SiOC\({}_{2}\)H\({}_{5}\), resulting in the formation of an Si-O-Si cross-linking network structure (Figure 4d). In the whole process, a small amount of water in air and solvent advanced the hydrolysis reaction slowly [44]. Figure 3: (**a**) Transmission electron microscopy (TEM) image; (**b**) size distribution, and; (**c**) high-resolution TEM (HRTEM) with crystalline interplanar spacing of CsPbBr\({}_{3}\) nanocrystals in IBOMA. Figure 2: (**a**) Photoluminescence (PL) (dark dash) and absorption (red line) spectra, and; (**b**) X-ray diffraction (XRD) pattern of CsPbBr\({}_{3}\) nanocrystals synthesized in isobornyl methacrylate (IBOMA). The present strategy can be expanded to synthesize blue and red emission CsPbX\({}_{3}\) by adding HCl or ZnI\({}_{2}\) to adjust the ratio of halide ions. Details of the process have been described in the Experimental section. The XRD patterns of the CsPbBr\({}_{3}\) nanocrystals and anion-exchanged samples showed the retention of cubic perovskite structure, and the shift of the XRD reflections was observed due to the difference of anion radius (Figure S3 in Supplementary Materials). Their PL spectra were adjustable from 430 to 620 nm (Figure S4 in Supplementary Materials) with narrow FWHM (10-40 nm), indicating this is a universal strategy. It is well known that the high sensitivity to the oxygen, moisture, light and temperature etc. leads to the poor stability of perovskites nanocrystals [13, 45, 46]. In order to enhance the stability for further application, in previous work, CsPbBr\({}_{3}\) nanocrystals were often combined with polymer by complicated processing [12]. Herein, by a facile UV curing process, CsPbBr\({}_{3}\)-IBOMA sol, can be cured directly into various shapes, because of the polymerization of the IBOMA monomer. The morphology of the CsPbBr\({}_{3}\) nanocrystals block sample was studied by TEM. As shown in Figure 5a, the CsPbBr\({}_{3}\) nanocrystals were uniformly distributed in the polymer matrix without phase separation or aggregation as expected, owing to the in-situ method. The particle size (\(11.6\pm 2.2\) nm) showed a slight increase compared with the sample before curing, because of the UV irradiation [47]. Furthermore, the emission spectrum was also unchanged, and only the emission intensity slightly reduced (Figure 5b), suggesting that the polymerization process of IBOMA does not affect the performance of nanocrystals. Figure 4: TEM images of CsPbBr\({}_{3}\) nanocrystals in IBOMA (**a**) with 3-aminopropyltriethoxysilane (APTES) and (**b**) without APTES after 2 weeks; (**c**) Fourier transform infrared (FTIR) spectrum of CsPbBr\({}_{3}\) nanocrystals in IBOMA; (**d**) illustration of formation of Si-O-Si cross-linking network. Figure 5: (**a**) TEM image of the CsPbBr\({}_{3}\) nanocrystals block sample; (**b**) fluorescence spectra of samples before and after be cured. High stability is very crucial for the practical application of CsPbBr\({}_{3}\) nanocrystals. Therefore, the light, air, moisture and thermal stability of as-synthesized nanocrystals were investigated. The PL spectra of the CsPbBr\({}_{3}\)-IBOMA block sample was measured at 5 h intervals under continuous irradiation with 395 nm UV LEDs (3W). As shown in Figure 6a, the shape and peak position of the emission spectra did not change significantly with the increase of irradiation time, indicating that the particle size of CsPbBr\({}_{3}\) nanocrystals was not affected by UV irradiation.