Perspective for aggregation-induced delayed fluorescence mechanism: A QM/MM study

Jie Liu; Jianzhong Fan; Kai Zhang; Yuchen Zhang; Chuan-Kui Wang; Lili Lin

doi:10.1088/1674-1056/aba2d9

Journals >Chinese Physics B >Volume 29 >Issue 8 >Page > Article

Chinese Physics B
Vol. 29, Issue 8, (2020)

Perspective for aggregation-induced delayed fluorescence mechanism: A QM/MM study

Jie Liu, Jianzhong Fan, Kai Zhang, Yuchen Zhang, Chuan-Kui Wang^†, and Lili Lin

Author Affiliations

Key Laboratory of Medical Physics and Image Processing & Shandong Provincial Engineering and Technical Center of Light Manipulations, School of Physics and Electronics, Shandong Normal University, Jinan 250358, China

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DOI: 10.1088/1674-1056/aba2d9 Cite this Article

Jie Liu, Jianzhong Fan, Kai Zhang, Yuchen Zhang, Chuan-Kui Wang, Lili Lin. Perspective for aggregation-induced delayed fluorescence mechanism: A QM/MM study[J]. Chinese Physics B, 2020, 29(8): Copy Citation Text

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(a) Chemical structure of DMF-BP-DMAC. (b) The atomic labels and the interesting bond lengths (B1, B2), bond angles (θ1, θ2), and dihedral angles (α1, α2, α3, and α4). (c) ONIOM model: surrounding molecules are regarded as low layer and the centered DMF-BP-DMAC is treated as high layer.

Fig. 1. (a) Chemical structure of DMF-BP-DMAC. (b) The atomic labels and the interesting bond lengths (B₁, B₂), bond angles (θ₁, θ₂), and dihedral angles (α₁, α₂, α₃, and α₄). (c) ONIOM model: surrounding molecules are regarded as low layer and the centered DMF-BP-DMAC is treated as high layer.

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Fig. 2. Geometry changes between two selected states for DMF-BP-DMAC in THF (a) and solid phase (b).

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Fig. 3. Energy levels and distributions of HOMO and LUMO for molecule in THF and solid phase (isovalue = 0.02).

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Fig. 4. Adiabatic excitation energies for DMF-BP-DMAC in THF (a) and solid phase (b).

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Fig. 5. Transition characteristics for S₁, T₁, and T₂ of DMF-BP-DMAC in THF (a) and transition characteristics for S₁, T₁, T₂, and T₃ of DMF-BP-DMAC in solid phase (b) (isovalue = 0.02). The value below every arrow represents the component of localized excitation in the corresponding transition.

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Fig. 6. The calculated HR factors of DMF-BP-DMAC in THF (a) and solid phase (b). The corresponding vibration modes are shown in inset.

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	THF		Solid
	λ/nm	f	λ/nm	f
B3LYP	590	0.0001	561	0.0068
PBE0	542	0.0001	517	0.0089
BMK	447	0.0006	430	0.0176
M062X	394	0.0223	396	0.0055
Exp.^a	534	–	510	–

Table 1. Emission wavelength and oscillator strength calculated by different functionals for DMF-BP-DMAC in tetrahydrofuran (THF) and solid phase.

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	THF				Solid
	S₀	S₁	T₁	T₂	S₀	S₁	T₁	T₂	T₃
B₁	1.23	1.27	1.27	1.27	1.22	1.26	1.26	1.25	1.25
B₂	1.43	1.44	1.43	1.43	1.42	1.45	1.44	1.44	1.44
θ₁	120.39	121.71	121.88	121.71	119.17	119.01	119.50	120.26	120.24
θ₂	119.27	120.20	119.92	120.17	119.96	120.58	120.38	120.05	120.05
α₁	27.62	32.42	32.88	33.71	−40.28	−40.62	−41.10	−34.94	−34.98
α₂	−79.38	−89.98	−67.94	−110.49	75.99	83.60	75.79	78.03	77.98
α₃	81.24	−91.10	−69.22	−111.09	84.53	81.04	73.37	79.48	79.42
α₄	39.06	0.20	−1.88	2.51	−38.53	−33.84	−34.64	−36.44	−36.52

Table 2. Geometry parameters of S₀, S₁, T₁, and T₂ states for DMF-BP-DMAC in THF and those of S₀, S₁, T₁, T₂, and T₃ states for DMF-BP-DMAC in solid phase. Bond lengths (B₁, B₂), bond angles (θ₁, θ₂), and dihedral angles (α₁, α₂, α₃, α₄) are marked in Fig. 1(b).

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		SOC^a/cm⁻¹	SOC^b/cm⁻¹	λ_S/meV	λ_T/meV	ΔE/meV	K_ISC/s⁻¹	K_RISC/s⁻¹
THF	S₁–T₁	0.01	0.44	124.2	15.6	24.1	1.98 × 10⁵	1.87 × 10¹⁰
	S₁–T₂	0.67	1.84	106.4	421.1	17.6	4.14 × 10⁶	6.57 × 10⁸
	S₁–T₃	0.33	0.34	271.5	292.3	-419.4	2.51 × 10⁷	2.5
Solid	S₁–T₁	0.19	0.39	52.1	24.5	47.7	4.81 × 10⁷	2.68 × 10⁷
	S₁–T₂	0.38	0.44	148.3	225.4	-146.5	2.00 × 10⁵	1.30 × 10⁸
	S₁–T₃	0.60	0.81	148.5	510.3	-146.5	3.47 × 10⁴	4.40 × 10⁸

Table 3. Spin–orbit coupling (SOC), reorganization energy (λ), energy difference (ΔE), intersystem crossing rates (K_ISC), and reverse intersystem crossing rates (K_RISC) between single excited states and triplet excited states.

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	THF	Solid
Kr/s−1	2.27 × 104	2.29 × 106
	2.18 × 107	4.79 × 107
	1.81 × 1010	4.25 × 108

Table 4. Calculated radiative rate (K_r), effective intersystem crossing rates (

K_{ISC}^{Cal}

), and effective reverse intersystem crossing rates (

K_{RISC}^{Cal}

Jie Liu, Jianzhong Fan, Kai Zhang, Yuchen Zhang, Chuan-Kui Wang, Lili Lin. Perspective for aggregation-induced delayed fluorescence mechanism: A QM/MM study[J]. Chinese Physics B, 2020, 29(8):

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