Room-temperature phosphorescence from bamboo fibers and designed materials

Recent developments in room-temperature phosphorescence (RTP) from biobased polymers have shown great promise in realizing sustainable RTP systems. Here, we introduce an efficient “top-down” method to achieve RTP biofibers using sixteen species of bamboo following partial delignification (B-fibers). The photophysical characterization combined with structural, surface and chemical inquiries (XRD, XPS, FTIR) along with DFT calculations revealed the fundamental reasons for RTP, associated with the interactions between cellulose, hemicelluloses and the residual lignin. Multiple emissive oxygen-containing clusters and aromatic chromophores in the B-fibers were shown to be RTP-active (wavelengths going from 450 to 530 nm at an increased excitation from 240 to 360 nm). Green afterglow with a lifetime of 294.9 ms (excitation wavelength = 270 nm) was observed while blue fluorescence and long-lived yellow-green RTP took place under 365 nm irradiation. Such effects were modulated by the crystalline environment and hydrogen bonding interactions. The RTP emission of the B-fibers was found to be sensitive to temperature, excitation and humidity. Moreover, when combined with a water-soluble fluorescent dye (following simple immersion), red afterglow emission was demonstrated under the effect of energy-transfer. Following these results, we synthesized functional luminescent materials (paper, films, textiles and aerogels), proposed herein as practical, sustainable and compostable choices for photoexcitation in the visible range.