The folder “Figure 2” contains normalised UV/Vis absorption and emission spectra of p-O-TPE (in 50:50 by vol EtOH/THF) and PDI-Sil (in THF). The emission spectra were recorded at front-face configurations, with excitation wavelength of 380 and 520 nm used for p-O-TPE and PDI-Sil, respectively.

The folder “Figure 3” contains the emission spectra (λem = 370 nm) of p-O-TPE-dU(600) with various concentrations recorded using front-face configuration (3b), PLQY of p-O-TPE-dU(600) with various concentrations measured with excitation wavelength of 400 nm (3c) and the UV/Vis transmittance spectra of p-O-TPE-dU(600) with various concentrations.

The folder “Figure 4” contains the emission spectra of dU(600) ureasils (2 cm × 2 cm × 0.3 cm) measured with front-face (4a) and edge (4b) configurations, with various concentration ratios between p-O-TPE and PDI-Sil, and excitation wavelength of 370 nm.

The folder “Figure S1” contains Photoluminescence excitation (λem = 650 nm) and (b) emission spectra (λex = 350 nm) of dU(600) waveguides, measured using front-face configurations.

The folder “Figure S3” contains the normalised excitation spectra (a-e, λem = 650 nm) of p-O-TPE-dU(600), p-O-TPE-PDI-Sil-dU(600) and PDI-Sil-dU(600) with varying concentration ratios between p-O-TPE and PDI-Sil. A concentration ratio of 1:1 represents 0.005 wt% of p-O-TPE and 0.005 wt% of PDI-Sil.

The folder “Figure S4” contains the normalised emission spectra (a-e, λex = 370 nm) of p-O-TPE-dU(600), p-O-TPE-PDI-Sil-dU(600) and PDI-Sil-dU(600) with varying concentration ratios between p-O-TPE and PDI-Sil. A concentration ratio of 1:1 represents 0.005 wt% of p-O-TPE and 0.005 wt% of PDI-Sil.

The folder “Figure S7” contains the normalised emission spectra (λex = 530 nm) of PDI-Sil-dU(600) samples with varying concentrations of PDI-Sil (0.0005 to 0.05 wt%), recorded with front-face configurations.

The folder “Figure S9” contains the UV/Vis transmittance spectra of dU(600), p-O-TPE-dU(600) (concentrations of p-O-TPE = 0.05 wt%), PDI-Sil-dU(600) (concentration of PDI-Sil = 0.05 wt%) and p-O-TPE-PDI-Sil-dU(600) (concentration of both p-O-TPE and PDI-Sil = 0.05 wt%). The dimension of the samples is 4.5 cm × 4.5 cm × 0.3 cm.

The folder “Figure S10” contains the UV/Vis absorption spectra of dU(600), p-O-TPE-dU(600) (concentrations of p-O-TPE = 0.05 wt%), PDI-Sil-dU(600) (concentration of PDI-Sil = 0.05 wt%) and p-O-TPE-PDI-Sil-dU(600) (concentration of both p-O-TPE and PDI-Sil = 0.05 wt%). The dimension of the samples is 4.5 cm × 4.5 cm × 0.3 cm.