Sequential Chiral-Layer Processing for Large Chiroptical Responses in Polymer Films and CP-LEDs
- 1Department of Physics
- 2National Taiwan Normal University
Abstract
Chiral small molecules can induce chiroptical responses in otherwise achiral fluorescent polymers, making these materials relevant to circularly polarized lightemitting materials and devices. Sequential deposition offers a route to chiroptical polymer films when a fluorescent polymer and a chiral small molecule cannot be readily co-processed from the same solvent. Here, poly(9,9-dioctylfluorene-altbithiophene) (F8T2) and a chiral inducer are deposited as initially separate layers from orthogonal solvents. A chiroptical response develops after thermal annealing, after which the excess inducer is reduced by selective ethanol treatment. With R-DbHP, the apparent peak absorption dissymmetry factor (|gabs|) increases from 0.09 for an optimized blend film to 0.35 for the sequentially processed film. With R-5011, the apparent film value reaches 1.06, and CP-LEDs show |gEL| up to 1.02. Across two independently fabricated devices per condition, the external quantum efficiency was 0.16–0.17% without EtOH treatment and 0.20–0.27% with treatment, and the corresponding turn-on voltages were 9V and 7V; the peak gEL remains similar, whereas the maximum luminance is lower in the treated devices. These device comparisons are exploratory and no statistical inference is made. The CD-derived values are also treated as apparent because complete polarization-artifact controls and independent validation of the largest raw ellipticities were not available. Within these limitations, the results identify sequential chiral-layer processing as a potential alternative to bulk co-doping in polymer CP-LEDs.
Related
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BibTeX
@misc{chen2026sequential,
title = {{Sequential Chiral-Layer Processing for Large Chiroptical Responses in Polymer Films and CP-LEDs}},
author = {Hsin-Tso Chen},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008146/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008146/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Sequential Chiral-Layer Processing for Large Chiroptical Responses in Polymer Films and CP-LEDs
AU - Hsin-Tso Chen
PY - 2026
DA - 2026/09/01
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008146/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008146/v1
AB - Chiral small molecules can induce chiroptical responses in otherwise achiral fluorescent polymers, making these materials relevant to circularly polarized lightemitting materials and devices. Sequential deposition offers a route to chiroptical polymer films when a fluorescent polymer and a chiral small molecule cannot be readily co-processed from the same solvent. Here, poly(9,9-dioctylfluorene-altbithiophene) (F8T2) and a chiral inducer are deposited as initially separate layers from orthogonal solvents. A chiroptical response develops after thermal annealing, after which the excess inducer is reduced by selective ethanol treatment. With R-DbHP, the apparent peak absorption dissymmetry factor (|gabs|) increases from 0.09 for an optimized blend film to 0.35 for the sequentially processed film. With R-5011, the apparent film value reaches 1.06, and CP-LEDs show |gEL| up to 1.02. Across two independently fabricated devices per condition, the external quantum efficiency was 0.16–0.17% without EtOH treatment and 0.20–0.27% with treatment, and the corresponding turn-on voltages were 9V and 7V; the peak gEL remains similar, whereas the maximum luminance is lower in the treated devices. These device comparisons are exploratory and no statistical inference is made. The CD-derived values are also treated as apparent because complete polarization-artifact controls and independent validation of the largest raw ellipticities were not available. Within these limitations, the results identify sequential chiral-layer processing as a potential alternative to bulk co-doping in polymer CP-LEDs.
ER -