TY - JOUR
T1 - Polarizable H-Bond Concept in Aromatic Poly(thiourea)s
T2 - Unprecedented High Refractive Index, Transmittance, and Degradability at Force to Enhance Lighting Efficiency
AU - Watanabe, Seigo
AU - Cavinato, Luca M.
AU - Calvi, Vladimir
AU - van Rijn, Richard
AU - Costa, Rubén D.
AU - Oyaizu, Kenichi
N1 - Publisher Copyright:
© 2024 The Authors. Advanced Functional Materials published by Wiley-VCH GmbH.
PY - 2024/10/15
Y1 - 2024/10/15
N2 - Developing transparent and highly refractive environmentally friendly polymers has not been realized yet toward sustainable optoelectronics. This work describes poly(thiourea)s (PTUs) design following a new “polarizable group synergy” concept, combining highly polarizable hydrogen bonding groups and aromatic-based spacers to form densely packed and high-refractive-index polymer networks. Specifically, PTUs containing m- and p-phenylene spacers exhibit an easy synthesis, high thermostability (Tg = 159 °C), visible transparency (>92%T at 1 µm-film), ultra-high refractive index (nD = 1.81) based on the random H-bonding arrays with a high packing constant (Kp = 0.738), and straightforward preparation of flexible films via solvent-based techniques. Capitalizing on these assets, PTU-films are integrated into benchmark graphene-based lighting device architectures based on the light-emitting electrochemical cells (LECs) concept. A joint optical modeling and experimental validation confirm the increase in external quantum efficiency expected by the enhanced light out-coupling of PTU-films. Finally, PTUs are efficiently depolymerized to low molecular weight compounds by simply adding diamines under heating, following the dynamic covalent bond exchange between thiourea moieties. Overall, this work highlights the PTU family as new promising materials with a unique polarizable H-bond design to meet efficient and sustainable thin-film lighting devices.
AB - Developing transparent and highly refractive environmentally friendly polymers has not been realized yet toward sustainable optoelectronics. This work describes poly(thiourea)s (PTUs) design following a new “polarizable group synergy” concept, combining highly polarizable hydrogen bonding groups and aromatic-based spacers to form densely packed and high-refractive-index polymer networks. Specifically, PTUs containing m- and p-phenylene spacers exhibit an easy synthesis, high thermostability (Tg = 159 °C), visible transparency (>92%T at 1 µm-film), ultra-high refractive index (nD = 1.81) based on the random H-bonding arrays with a high packing constant (Kp = 0.738), and straightforward preparation of flexible films via solvent-based techniques. Capitalizing on these assets, PTU-films are integrated into benchmark graphene-based lighting device architectures based on the light-emitting electrochemical cells (LECs) concept. A joint optical modeling and experimental validation confirm the increase in external quantum efficiency expected by the enhanced light out-coupling of PTU-films. Finally, PTUs are efficiently depolymerized to low molecular weight compounds by simply adding diamines under heating, following the dynamic covalent bond exchange between thiourea moieties. Overall, this work highlights the PTU family as new promising materials with a unique polarizable H-bond design to meet efficient and sustainable thin-film lighting devices.
KW - easy degradability
KW - high refractive index
KW - light outcoupling
KW - light-emitting electrochemical cells
KW - polythiourea
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U2 - 10.1002/adfm.202404433
DO - 10.1002/adfm.202404433
M3 - Article
AN - SCOPUS:85189986254
SN - 1616-301X
VL - 34
JO - Advanced Functional Materials
JF - Advanced Functional Materials
IS - 42
M1 - 2404433
ER -