Understanding TADF: a joint experimental and theoretical study of DMAC-TRZ

Dhali, Rama; Huu, D. K. Andrea Phan; Bertocchi, Francesco; Sissa, Cristina; Terenziani, Francesca; Painelli, Anna

doi:10.1039/d0cp05982j

Cited by 39 publications

(83 citation statements)

References 60 publications

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“…Details of the model parametrization can be found in ref. 35, shortly, TD-DFT (Tamm Dancoff approximation, M062x functional, 6-31G(d) basis) was exploited to calculate the δ -dependence of the first few excited states in the singlet and triplet manifold. The first eight parameters in Table 1 were fixed to best reproduce the resulting PES, as well as the δ -dependence of the SOC matrix elements (ZORA).…”

Section: Setting Up the Model: Tadf In The Gas Phasementioning

confidence: 99%

Effective models for TADF: the role of the medium polarizability

2022

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Section: Setting Up the Model: Tadf In The Gas Phasementioning

confidence: 99%

Effective models for TADF: the role of the medium polarizability

2022

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“…Note that even if a molecule does not exhibit a sizeable PDM in the ground state, it can do so in the excited state, and directions of the respective PDM vectors can be different as well. This is particularly pronounced if the excited state has charge-transfer character, as it is the case for thermally activated delayed fluorescence (TADF) emitters, and can induce remarkable photophysical effects that are the subject of dedicated studies [38,39] but will not be discussed here.The focus of this review are polar molecules that show a non-vanishing net alignment of their PDMs in thin films, so-called spontaneous orientation polarization (SOP). [30] As indicated in Figure 2d, this leads to a macroscopic dielectric polarization P 0 which is related to the presence of interfacial charge densities σ of opposite sign at the interfaces to neighboring layers, if those are non-polar, and is described by an order parameter…”

Section: Materials and Phenomenamentioning

confidence: 99%

The Many Facets of Molecular Orientation in Organic Optoelectronics

Hofmann

Schmid

Brütting

2021

Advanced Optical Materials

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exploitation in devices has only recently become a major topic in organic optoelectronics. [10][11][12] Moreover, as different (and sometimes competing) effects can even occur in one and the same type of device application, their underlying principles and design rules need to be well understood.In this article, we review the current understanding of this emerging field of organic optoelectronics and discuss recent developments as well as some open issues.

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“…However, theoretical studies of TADF molecules taking into account the solid-state environment have so far been limited. [77,78,98,[115][116][117][118][119][120] In addition, among those theoretical investigations, little emphasis has been put on the host-guest amorphous state that is widely adopted for highly efficient TADF OLEDs. In this regard, theoretical investigations focusing on a host-guest amorphous state are highly desired to get insights into the interactions between the host materials and TADF emitters.…”

Section: Wwwadvopticalmatdementioning

confidence: 99%

Host‐Dopant Interaction between Organic Thermally Activated Delayed Fluorescence Emitter and Host Material: Insight into the Excited State

et al. 2021

Advanced Optical Materials

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rapidly, and the products based on OLEDs including smartphones, televisions, monitors, etc. are being commercialized.The utilization mechanism of the excitons determines the quantum efficiency of the devices. [13][14][15] OLEDs based on the conventional fluorescent materials can only harvest the singlet excitons for light emission, which results in an upper limit of only 25% for internal quantum efficiency (IQE). The phosphorescent OLEDs incorporating transition metals into the molecular framework of organic emitters represent a huge breakthrough, which demonstrated an IQE of nearly 100%. [16,17] However, phosphorescent emitters contain expensive transition metals, which increases the fabrication costs of the devices and limits their large-scale applications despite the high efficiency. Besides, the toxicity of heavy atoms is also a bothering issue. Thus, novel emission mechanisms are needed to improve both the efficiency and the cost issue. In this context, triplet-triplet annihilation (TTA, also known as P-type delayed fluorescence), [18] hybridized locally and charge transfer (HLCT, also known as the "hot exciton" mechanism), [19][20][21][22] and thermally activated delayed fluorescence (TADF) [23][24][25] are promising. Among them, TADF represents a successful mechanism for realizing high IQE up to 100% (Figure 1). In recent years, TADF emitters based on the multiresonance (MR-TADF) concept have drawn much research attention, which offer a perfect solution to achieving both high efficiency and high color purity. [1,3,6,26,27] Besides, TADF can be realized in purely organic emitters, which is merit for low-cost devices. In the TADF mechanism, the T 1 state can be converted to the S 1 state through a reserve intersystem crossing (RISC) facilitated by a small S 1 -T 1 energy gap (ΔE ST ). The fluorescence resulting from the S 1 on charge recombination is defined as prompt fluorescence with a short lifetime, while the fluorescence originating from the S 1 that is up converted from the T 1 state is defined as the delayed fluorescence with a long lifetime.TADF emitters are typically doped into a suitable organic matrix to address the quenching effects such as concentration quenching, triplet-triplet annihilation, singlet-triplet annihilation (STA), and triplet-polaron annihilation (TPA) to enhance the device efficiency and stability. [28][29][30][31][32][33] Thus, both host materials Organic light-emitting diodes (OLEDs) represent one of the most promising technologies for future displays and lighting sources, which have received extensive research attention. Purely organic thermally activated delayed fluorescence (TADF) emitters offer obvious advantages, including high efficiencies and low costs, and they are typically doped in host materials to achieve optimal device efficiencies. TADF emitters typically feature intramolecular charge transfer characteristics, and their excited states properties are sensitive to local environment, giving the implication that host materials can finely tune their emission properties...

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Understanding TADF: a joint experimental and theoretical study of DMAC-TRZ

Abstract: TADF offers a promising way to harvest triplets in OLED for improved efficiency. To concurrently optimize the dye inside the matrix, a thorough experimental and theoretical study is presented of a the TADF dye addressing environmental effects.

Cited by 39 publications

References 60 publications

Effective models for TADF: the role of the medium polarizability

Effective models for TADF: the role of the medium polarizability

The Many Facets of Molecular Orientation in Organic Optoelectronics

Host‐Dopant Interaction between Organic Thermally Activated Delayed Fluorescence Emitter and Host Material: Insight into the Excited State

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