A universal strategy for multicolor organic circularly polarized afterglow materials with high dissymmetry factors

Abstract

Materials with pure organic circularly polarized afterglow (CPA) have attracted significant attention due to their spatiotemporal-resolved optical properties, yet achieving simultaneous high dissymmetry factor (glum) and multicolor ultralong emission remains a challenge. Here, we establish a universal energy transfer-photon coupling strategy to realize CPA spanning from blue to red with record-high glum (up to 1.90) and ultralong lifetimes (>6 s). Systematic characterization of nonchiral donor-acceptor systems (TP-BPEA, TP-Fluo, etc.) reveals the absence of ground-state chiral centers (g_CD ≈ 0) and orientation artifacts (LD < 10^-7), confirming the key role of cholesteric liquid crystal polymer in chirality induction. This spatiotemporal synergy between energy transfer (wavelength modulation) and photonic engineering (polarization control) provides a framework for chiral photonic materials, with potential implications for multidimensional information encryption.

Keywords: afterglow; circularly polarized luminescence; liquid crystal; room-temperature phosphorescence.

Fig. 1.

Strategy and performance of pure organic CPA materials. (A) Schematic illustration of the assembly of multilayered films and the formation of multicolor pure organic CPA. (B) CPL performance of pure organic CPA materials based on CLCs [gray spheres refer to the organic CPA data from published results (–, –44)]

Fig. 2.

Photophysical properties of the OU-RTP film and multicolor luminescent films under ambient conditions. (A) Normalized steady-state photoluminescence (dashed line) and phosphorescence (solid line) spectra of TP-PVA film under ambient condition (TP:PVA = 3:1,000, w/w, λ_ex = 254 nm). (B) Decay curve of TP-PVA film (λ_ex = 254 nm, λ_em = 475 nm). (C) Delayed spectrum of TP-PVA film and absorption spectra of BPEA-PMMA, Fluo-PVB, DBT-PMMA, and NiR-PMMA films. (D) Delayed spectrum of TP-PVA film, TP-Fluo film, TP-DBT film, and TP-NiR film under ambient conditions (λ_ex = 254 nm). (E) CIE diagram calculated from (D). (F) Decay curves of TP-BPEA film (λ_ex = 254 nm, λ_em = 500 nm), TP-Fluo film (λ_ex = 254 nm, λ_em = 520 nm), TP-DBT film (λ_ex = 254 nm, λ_em = 560 nm), and TP-NiR film (λ_ex = 254 nm, λ_em = 620 nm). (G) Simplified Jablonski diagram to explain the possible mechanism for the radiative energy transfer process. Abs. = absorption, Fluo. = fluorescence, Phos. = phosphorescence, ISC = intersystem crossing.

Fig. 3.

Structural and photophysical properties of CLCP films. (A) Schematic illustration of the preparation process of CLCP films. (B) Normalized reflection spectra of CLCP films doped with different ratios of S/R-5011. (C) Cross-sectional SEM images of CLCP film (the scale bar in the SEM image above is 20 μm, and the below is 3 μm). (D) CD spectra of CLCP films doped with different ratios of S/R-5011. Inset: POM images of the CLCP film doped with different ratios of S/R-5011.

Fig. 4.

Photophysical properties of the triple-layered composite films under ambient conditions. (A) CPL spectra and (B) g_lum spectra of the triple-layered composite films (λ_ex = 254 nm). (C) Illustration of three different CPL generation channels based on different layer sequences: (I) TP-PVA, NiR-PMMA, LR-Red; (II) TP-PVA, LR-Blue, NiR-PMMA; (III) LR-Red, TP-PVA, NiR-PMMA. (D) The lifetimes of the triple-layered composite films (λ_ex = 254 nm, delay time = 0.1 ms). The angle-dependent g_lum (E) and time-resolved g_lum (F) at 475 nm of TP-LR-Blue and TP-LS-Blue, 500 nm of TP-BPEA-LR-Cyan and TP-BPEA-LS-Cyan, 520 nm of TP-Fluo-LR-Green and TP-Fluo-LS-Green, 560 nm of TP-DBT-LR-Yellow and TP-DBT-LS-Yellow, and 620 nm of TP-NiR-LR-Red and TP-NiR-LS-Red.

Fig. 5.

Application of pure organic CPA materials. Construction and decryption of a multilevel information encryption system based on NiR, TP@NiR, TP-NiR, TP-BPEA-LR-Cyan, and TP-BPEA-LS-Cyan films. One layout can yield seven different codes when viewed at different timings and through different polarizers.