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Di Maiolo F, Phan Huu DKA, Giavazzi D, Landi A, Racchi O, Painelli A. Shedding light on thermally-activated delayed fluorescence. Chem Sci 2024; 15:5434-5450. [PMID: 38638233 PMCID: PMC11023041 DOI: 10.1039/d4sc00033a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 02/17/2024] [Indexed: 04/20/2024] Open
Abstract
Thermally activated delayed fluorescence (TADF) is a hot research topic in view of its impressive applications in a wide variety of fields from organic LEDs to photodynamic therapy and metal-free photocatalysis. TADF is a rare and fragile phenomenon that requires a delicate equilibrium between tiny singlet-triplet gaps, sizable spin-orbit couplings, conformational flexibility and a balanced contribution of charge transfer and local excited states. To make the picture more complex, this precarious equilibrium is non-trivially affected by the interaction of the TADF dye with its local environment. The concurrent optimization of the dye and of the embedding medium is therefore of paramount importance to boost practical applications of TADF. Towards this aim, refined theoretical and computational approaches must be cleverly exploited, paying attention to the reliability of adopted approximations. In this perspective, we will address some of the most important issues in the field. Specifically, we will critically review theoretical and computational approaches to TADF rates, highlighting the limits of widespread approaches. Environmental effects on the TADF photophysics are discussed in detail, focusing on the major role played by dielectric and conformational disorder in liquid solutions and amorphous matrices.
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Affiliation(s)
- Francesco Di Maiolo
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - D K Andrea Phan Huu
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Davide Giavazzi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Andrea Landi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Ottavia Racchi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
| | - Anna Painelli
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma Parco Area delle Scienze 17/A 43124 Parma Italy
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Bardi B, Giavazzi D, Ferrari E, Iagatti A, Di Donato M, Phan Huu DKA, Di Maiolo F, Sissa C, Masino M, Lapini A, Painelli A. Solid state solvation: a fresh view. MATERIALS HORIZONS 2023; 10:4172-4182. [PMID: 37522331 DOI: 10.1039/d3mh00988b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
The design of efficient organic electronic devices, including OLEDs, OPVs, luminescent solar concentrators, etc., relies on the optimization of relevant materials, often constituted by an active (functional) dye embedded in a matrix. Understanding solid state solvation (SSS), i.e. how the properties of the active dye are affected by the matrix, is therefore an issue of fundamental and technological relevance. Here an extensive experimental and theoretical investigation is presented shedding light on this, somewhat controversial, topic. The spectral properties of the dye at equilibrium, i.e. absorption and Raman spectra, are not affected by the matrix dynamics. Reliable estimates of the matrix polarity are then obtained from an analysis of the micro-Raman spectra of polar dyes. Specifically, to establish a reliable polarity scale, the spectra of DCM or NR dispersed in amorphous matrices are compared with the spectra of the same dyes in liquid solvents with known polarity. On the other hand, steady-state emission spectra obtained in solid matrices depend in a highly non-trivial way on the matrix polarity and its dynamics. An extensive experimental and theoretical analysis of the time-resolved emission spectra of NR in a very large time window (15 fs-15 ns) allows us to validate this dye as a good probe of the dielectric dynamics of the surrounding medium. We provide a first assessment of the relaxation dynamics of two matrices (mCBPCN and DPEPO) of interest for OLED application, unambiguously demonstrating that the matrix readjusts for at least 15 ns after the dye photoexcitation.
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Affiliation(s)
- Brunella Bardi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Davide Giavazzi
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Elena Ferrari
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Alessandro Iagatti
- CNR-INO (Istituto Nazionaledi Ottica), Largo Fermi 6, 50125 Firenze, Italy
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Mariangela Di Donato
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
- ICCOM-CNR, via Madonna del Piano 10, I-50019 Sesto Fiorentino, FI, Italy
| | - D K Andrea Phan Huu
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Francesco Di Maiolo
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Cristina Sissa
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Matteo Masino
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
| | - Andrea Lapini
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
- LENS (European Laboratory for Non-Linear Spectroscopy), Via N. Carrara 1, 50019, Sesto Fiorentino, FI, Italy
| | - Anna Painelli
- Dept. Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area delle Scienze 17/A, 43124 Parma, Italy.
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Suresh SM, Zhang L, Matulaitis T, Hall D, Si C, Ricci G, Slawin AMZ, Warriner S, Beljonne D, Olivier Y, Samuel IDW, Zysman-Colman E. Judicious Heteroatom Doping Produces High-Performance Deep-Blue/Near-UV Multiresonant Thermally Activated Delayed Fluorescence OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2300997. [PMID: 37140188 DOI: 10.1002/adma.202300997] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/26/2023] [Indexed: 05/05/2023]
Abstract
Two multiresonant thermally activated delayed fluorescence (MR-TADF) emitters are presented and it is shown how further borylation of a deep-blue MR-TADF emitter, DIDOBNA-N, both blueshifts and narrows the emission producing a new near-UV MR-TADF emitter, MesB-DIDOBNA-N, are shown. DIDOBNA-N emits bright blue light (ΦPL = 444 nm, FWHM = 64 nm, ΦPL = 81%, τd = 23 ms, 1.5 wt% in TSPO1). The deep-blue organic light-emitting diode (OLED) based on this twisted MR-TADF compound shows a very high maximum external quantum efficiency (EQEmax ) of 15.3% for a device with CIEy of 0.073. The fused planar MR-TADF emitter, MesB-DIDOBNA-N shows efficient and narrowband near-UV emission (λPL = 402 nm, FWHM = 19 nm, ΦPL = 74.7%, τd = 133 ms, 1.5 wt% in TSPO1). The best OLED with MesB-DIDOBNA-N, doped in a co-host, shows the highest efficiency reported for a near-UV OLED at 16.2%. With a CIEy coordinate of 0.049, this device also shows the bluest EL reported for a MR-TADF OLED to date.
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Affiliation(s)
- Subeesh Madayanad Suresh
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Le Zhang
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Tomas Matulaitis
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - David Hall
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium
| | - Changfeng Si
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Gaetano Ricci
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, Université de Namur, Rue de Bruxelles, 61, Namur, 5000, Belgium
| | - Alexandra M Z Slawin
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Stuart Warriner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK
| | - David Beljonne
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium
| | - Yoann Olivier
- Laboratory for Chemistry of Novel Materials, University of Mons, Mons, 7000, Belgium
- Laboratory for Computational Modeling of Functional Materials, Namur Institute of Structured Matter, Université de Namur, Rue de Bruxelles, 61, Namur, 5000, Belgium
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
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Sensitivity of the hidden TADF to the linking topology of di-tert-butyl-carbazolyl and benzonitrile moieties in the molecules of emitters or hosts intended for efficient blue OLEDs. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
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Jovaišaitė J, Baronas P, Jonusauskas G, Gudeika D, Gruodis A, Gražulevičius JV, Juršėnas S. TICT compounds by design: comparison of two naphthalimide-π-dimethylaniline conjugates of different lengths and ground state geometries. Phys Chem Chem Phys 2023; 25:2411-2419. [PMID: 36598166 DOI: 10.1039/d2cp04250a] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Two new twisted intramolecular charge transfer (TICT) donor-π-acceptor compounds were designed by combining a well-known electron acceptor naphthalimide unit with a classic electron donor dimethylaniline through two types of different rigid linkers. The combined steady-state and time-resolved spectroscopy of molecules in solvents of different polarities in comparison to solid-state solvation experiments of doped polymer matrixes of different polarities allowed distinguishing between solvation and conformation determined processes. The photophysical measurements revealed that non-polar solutions possess high fluorescence quantum yields of up to 70% which is a property of pre-twisted/planar molecules in the excited charge transfer (CT) states. The increase of polarity allows tuning the Stokes shift through all the visible wavelength range up to 8601 cm-1 which is accompanied by a three orders of magnitude drop of fluorescence quantum yields. This is a result of the emerged TICT states as dimethylaniline twists to a perpendicular position against the naphthalimide core. The TICT reaction of molecules enables an additional non-radiative excitation decay channel, which is not present if the twisting is forbidden in a rigid polymer matrix. Transient absorption spectroscopy was employed to visualize the excited state dynamics and to obtain the excited state reaction constants, revealing that TICT may occur from both the Franck-Condon region and the solvated pre-twisted/planar CT states. Both molecules undergo the same photophysical processes, however, a longer linker and thus a higher excited state dipole moment determines the faster excited state reactions.
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Affiliation(s)
- Justina Jovaišaitė
- Institute of Photonics and Nanotechnology, Vilnius University, Saulėtekio Ave. 3, LT-10257 Vilnius, Lithuania.
| | - Paulius Baronas
- Institute of Photonics and Nanotechnology, Vilnius University, Saulėtekio Ave. 3, LT-10257 Vilnius, Lithuania.
| | - Gediminas Jonusauskas
- Laboratoire Ondes et Matiére d'Aquitaine, Bordeaux University, UMR CNRS 5798, 351 cours de la Libération, 33405 Talence, France
| | - Dalius Gudeika
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilėnų rd. 19, LT-50254 Kaunas, Lithuania
| | - Alytis Gruodis
- Institute of Chemical Physics, Vilnius University, Saulėtekio Ave. 3, LT-10257 Vilnius, Lithuania
| | - Juozas V Gražulevičius
- Department of Polymer Chemistry and Technology, Kaunas University of Technology, Radvilėnų rd. 19, LT-50254 Kaunas, Lithuania
| | - Saulius Juršėnas
- Institute of Photonics and Nanotechnology, Vilnius University, Saulėtekio Ave. 3, LT-10257 Vilnius, Lithuania.
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Karaman M, Kumar Gupta A, Madayanad Suresh S, Matulaitis T, Mardegan L, Tordera D, Bolink HJ, Wu S, Warriner S, Samuel ID, Zysman-Colman E. Ionic multiresonant thermally activated delayed fluorescence emitters for light emitting electrochemical cells. Beilstein J Org Chem 2022; 18:1311-1321. [PMID: 36225727 PMCID: PMC9520854 DOI: 10.3762/bjoc.18.136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 09/08/2022] [Indexed: 11/30/2022] Open
Abstract
We designed and synthesized two new ionic thermally activated delayed fluorescent (TADF) emitters that are charged analogues of a known multiresonant TADF (MR-TADF) compound, DiKTa. The emission of the charged derivatives is red-shifted compared to the parent compound. For instance, DiKTa-OBuIm emits in the green (λPL = 499 nm, 1 wt % in mCP) while DiKTa-DPA-OBuIm emits in the red (λPL = 577 nm, 1 wt % in mCP). In 1 wt % mCP films, both emitters showed good photoluminescence quantum yields of 71% and 61%, and delayed lifetimes of 316.6 μs and 241.7 μs, respectively, for DiKTa-OBuIm and DiKTa-DPA-OBuIm, leading to reverse intersystem crossing rates of 2.85 × 103 s−1 and 3.04 × 103 s−1. Light-emitting electrochemical cells were prepared using both DiKTa-OBuIm and DiKTa-DPA-OBuIm as active emitters showing green (λmax = 534 nm) and red (λmax = 656 nm) emission, respectively.
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Affiliation(s)
- Merve Karaman
- Department of Material Science and Engineering, Faculty of Engineering and Architecture, Izmir Katip, Celebi University, Cigli, 35620-Izmir, Turkey
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
| | - Abhishek Kumar Gupta
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Subeesh Madayanad Suresh
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
| | - Tomas Matulaitis
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
| | - Lorenzo Mardegan
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna (Valencia), Spain
| | - Daniel Tordera
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna (Valencia), Spain
| | - Henk J Bolink
- Instituto de Ciencia Molecular (ICMol), Universidad de Valencia, C/Catedrático J. Beltrán 2, 46980 Paterna (Valencia), Spain
| | - Sen Wu
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
| | - Stuart Warriner
- School of Chemistry, University of Leeds, Woodhouse Lane, Leeds, UK
| | - Ifor D Samuel
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, UK, KY16 9ST
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Phan Huu DKA, Saseendran S, Dhali R, Franca LG, Stavrou K, Monkman A, Painelli A. Thermally Activated Delayed Fluorescence: Polarity, Rigidity, and Disorder in Condensed Phases. J Am Chem Soc 2022; 144:15211-15222. [PMID: 35944182 PMCID: PMC9413221 DOI: 10.1021/jacs.2c05537] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We present a detailed and comprehensive picture of the photophysics of thermally activated delayed fluorescence (TADF). The approach relies on a few-state model, parametrized ab initio on a prototypical TADF dye, that explicitly accounts for the nonadiabatic coupling between electrons and vibrational and conformational motion, crucial to properly address (reverse) intersystem crossing rates. The Onsager model is exploited to account for the medium polarity and polarizability, with careful consideration of the different time scales of relevant degrees of freedom. TADF photophysics is then quantitatively addressed in a coherent and exhaustive approach that accurately reproduces the complex temporal evolution of emission spectra in liquid solvents as well as in solid organic matrices. The different rigidity of the two environments is responsible for the appearance in matrices of important inhomogeneous broadening phenomena that are ascribed to the intertwined contribution from (quasi)static conformational and dielectric disorder.
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Affiliation(s)
- D K Andrea Phan Huu
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy
| | - Sangeeth Saseendran
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy
| | - Rama Dhali
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy
| | | | - Kleitos Stavrou
- Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K
| | - Andrew Monkman
- Department of Physics, Durham University, South Road, Durham DH1 3LE, U.K
| | - Anna Painelli
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, 43124 Parma, Italy
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