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1 Electronic upplementary Material (EI) for ChemComm. his journal is he Royal ociety of Chemistry 06 Electronic upplementary Material (EI) for Chemical Communications his journal is he Royal ociety of Chemistry 05 Electronic upplementary Information for An Effective Host Material with hermally Activated Delayed Fluorescence Formed by Confined Conjugation for Red Phosphorescent Organic Light-Emitting Diodes Xiang-Yang Liu, Feng Liang, Yi Yuan, Lin-ong Cui, Zuo-Quan Jiang,* Liang-heng Liao* Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional ano & oft Materials (FUOM), oochow University uzhou, Jiangsu 53, China. cheme ynthetic routes of PrDPhAc. Fig. GA and DC (inset) curves of PrDPhAc. Fig. UP spectra of PrDPhAc. Fig. 3 Cyclic voltammograms of PrDPhAc. Fig. 4 Fluorescence spectra of PrDPhAc in different solvents (0-5 M). able ummary of the physical properties of PrDPhAc. able Data extracted from the transient characterization of PrDPhAc solution. Fig. 5 Molecular structures and representative energy level diagram of the materials.

2 Fig. 6 Current density-voltage-luminance (J-V-L) characteristics and EL spectra at 5 ma cm - for PrDPhAc based device. able 3 ummary of electroluminescence data for red OLED. Experimental ection H MR and 3 C MR spectra were recorded on a Bruer 400 spectrometer at room temperature. Mass spectra were recorded on a hermo IQ mass spectrometer using a direct exposure probe. UV-vis absorption spectra were recorded on a Perin Elmer Lambda 750 spectrophotometer. PL spectra and phosphorescent spectra were recorded on a Hitachi F-4600 fluorescence spectrophotometer. Differential scanning calorimetry (DC) was performed on a A DC 00 unit at a heating rate of 0 o C min - under nitrogen. he glass transition temperatures ( g ) were determined from the second heating scan. hermogravimetric analysis (GA) was performed on a A D 960 instrument at a heating rate of 0 o C min - under nitrogen. emperature at 5% weight loss was used as the decomposition temperature ( d ). Cyclic voltammetry (CV) was carried out on a CHI600 voltammetric analyzer at room temperature with ferrocenium-ferrocene (Fc + /Fc) as the internal standard. Deaerated dichloromethane was used as solvent for oxidation scan with tetrabutylammonium hexafluorophosphate (BAPF6) (0. M) as the supporting electrolyte. he cyclic voltammograms were obtained at scan rate of 0. V s -. Ultra- Violet Photoemission pectroscopy (UP) analysis was carried out with an unfiltered He I (. ev) gas discharge lamp and a hemispherical analyzer, which was made by KRAO AALYICAL HIMADZU GROUP COMPAY. DF calculations were performed using B3LYP/6-3g(d) basis set using Gaussian 09.

3 Fabrication and measurement of OLED devices he OLEDs were fabricated on the indium-tin oxide (IO) coated transparent glass substrates, the IO conductive layer has a thicness of ca. 00 nm and a sheet resistance of ca. 30 Ω per square. he substrates was cleaned with ethanol, acetone and deionized water, and then dried in an oven, finally exposed to UV ozone for 30 min. All of the organic materials and metal layers under a vacuum of ca. 0-6 orr. Four identical OLED devices were formed on each of the substrates and the emission area of 0.09 cm for each device. he EL performances of the blue and white devices were measured with a PHOO REEARCH pectracan PR 655 PHOOMEER and a KEIHLEY 400 ourcemeter constant current source at room temperature. I COOCH 3 MgCl H COOCH 3 H Cu, K CO 3, o-dcb H HF, 0 o C H OH HCl, HOAc Cl Cl Pd (dba) 3, -Phos, t-buoa, oluene PrDPhAc cheme ynthetic routes of PrDPhAc. Preparation of 9,9-diphenylacridane and,6-bis(9,9-diphenylacridin-0(9h)- yl)pyrazine (PrDPhAc).

4 All chemicals and reagents were used as received from commercial sources without further purification. HF was purified by PURE OLV (Innovative echnology) purification system. H MR and 3 C MR spectra were recorded on a Bruer 400 spectrometer at room temperature. Mass spectra were recorded on a hermo IQ mass spectrometer using a direct exposure probe. Preparation of 9,9-diphenylacridane [] : I COOCH 3 MgCl H COOCH 3 H Cu, K CO 3, o-dcb H HF, 0 o C H OH HCl, HOAc A mixture of methyl anthranilate (0 g, 3 mmol), iodobenzene (6.9 g, 3 mmol), K CO 3 (36.4 g, 64 mmol), and copper powder (0.7 g,.64 mmol) was scattered in,- dichlorobenzene (o-dcb) and stirred for 0 hours at 80 C under argon. After the reaction cooling to room temperature, filtered and washed with dichloromethane (DCM). Remove the solvent under reduced pressure and the crude product was purified by column chromatography using petroleum ether/dichloromethane (/, v/v) to afford the pure product as a colourless oil (3 g, 77%). his product used in the next step needn t to further purification. he colourless oil (0 g, 44 mmol) was dissolved in 80 ml tetrahydrofuran (HF) in a 500 ml chlen tube under argon and cooled to 0 o C, and then phenylmagnesium chloride (PhMgCl, M in HF, 66 ml, 3 mmol) was added dropwise under stirred. After h reaction at 0 o C, the mixture was gradually warmed up to room temperature

5 overnight. he reaction was quenched by water (5 ml). Put the mixture into 50 ml water, the product was extracted with EtOAc (3 50 ml), the combined organic layers were washed with brine and dried over anhydrous sodium sulfate (ao 4 ). Filtrated and evaporated under reduce pressure to afford a yellow oil or yellow soild (4 g), which was directly used in the next reaction without further purification. he crude product was dissolved in 00 ml acetic acid (HOAc) under 70 o C and 0 ml hydrochloric acid (HCl) was added dropwise under stirred. he mixture was reaction overnight at 70 o C. After the reaction cooling to room temperature, filtered and washed with absolute ethyl alcohol, and dried under vacuum to give 9,9-diphenylacridane as white powder ( g, ~90%) Preparation of,6-bis(9,9-diphenylacridin-0(9h)-yl)pyrazine (PrDPhAc): H Cl Cl Pd (dba) 3, -Phos, t-buoa, oluene 9,9-diphenylacridane (0 g, 30 mmol),,6-dichloropyrazine (4.47 g, 30 mmol), tris(dibenzylideneacetone)dipalladium(0) (Pd (dba) 3, 0.7 g, 0.3 mmol), - dicyclohexylphosphino-',6'-dimethoxy-,'-biphenyl (-Phos, 0.37 g, 0.9 mmol), sodium t-butoxide (t-buoa, 5.76 g, 60 mmol) were dissolved in toluene under argon and heated to 0 o C. After 0 h reaction under stirring, the reaction was cooled to room temperature and 00 ml water was added. he product was extracted with dichloromethane (DCM, 3 00 ml), the combined organic layers were washed with

6 brine and dried over anhydrous sodium sulfate (ao 4 ). Filtered and evaporated under reduced pressure. he crude product was purified by column chromatography using petroleum ether/dichloromethane (/, v/v) to give,6-bis(9,9-diphenylacridin-0(9h)- yl)pyrazine (PrDPhAc) as a yellow powder (7.4 g, 65%). H MR (400 MHz, CDCl 3 ): δ 7.48 (m, 4H), (m, 6H), (m, 6H), 6.97 (m, 4H), (m, 8H) ppm. 3 C MR (00 MHz, CDCl 3 ): δ 49.65, 44.66, 40.80, 39.8, 30.43, 9.9, 8.44, 7.66, 6.66 (d, J = 6.3 Hz), 3.66,.80, 58. ppm. M m/z: Anal. Calcd for C 54 H 38 4 (%): C 87.30, H 5.6, 7.54; found: C 87.46, H 5.5, 7.36.

7 Figures Fig. GA and DC (inset) curves of PrDPhAc. Fig. UP spectrum of PrDPhAc.

8 Fig. 3 Cyclic voltammograms of PrDPhAc. he electrochemical properties of PrDPhAc was measured by cyclic voltammetry (CV) using typically tri-electrode configuration method with ferrocene as the internal standard in dichloromethane solution with 0. M n-bu 4 PF 6 as the supporting electrolyte. We calculated the HOMO level of PrDPhAc is ev, from the onset of the first oxidation wave. he LUMO of PrDPhAc can be gained from the onset of the reduction wave, is 3.36 ev. Fig. 4 Fluorescence spectra of PrDPhAc in different solvents (0-5 M).

9 able ummary of the physical properties of PrDPhAc. Host Abs λ max a PL λ max a g b d c E g d E e HOMO f LUMO g ΔE [nm] [nm] [ o C] [ o C] [ev] [ev] [ev] [ev] [ev] PrDPhAc h /0.07 i a) Measured in CH Cl solution at room temperature. b) g : Glass transition temperature. c) d : Decomposition temperature. d) E g : Band gap energies were calculated from the corresponding absorption onset in CH Cl solution. e) E : Measured in -MeHF glass matrix at 77 K. f) HOMO levels were calculated from UP date. g) LUMO levels, calculated from the HOMO and E g. h) ΔE : singlet-triplet energy difference, based on DF calculations. i) ΔE : estimated from the difference of onsets of the PL and Phos. In this study, the ratio between prompt and delayed components was calculated from transient PL measurements. he intensity ratio between prompt (r ) and delayed (r ) components were determined using emission life time (τ, τ ) and fitting parameter (Α, Α ) as follow. I e τ τ t A e A r A τ A τ A τ r A τ A τ A τ And then, prompt fluorescence efficiency (Φ PF ) and delayed fluorescence efficiency (Φ DF ) were determined using intensity ratio (r, r ) and total emission quantum yield (Φ total ). [] Φ total Φ PF Φ DF Φ PF r Φ total

10 Φ DF r Φ total It is nown that the ADF is significant only if the two following conditions are met: (i) reasonably high probability of intersystem crossing, i.e., high quantum yield of triplet formation η, where η η r nr η τ ;, in which,, therefore r nr and (ii) sufficiently high probability of subsequent R, i.e., high quantum yield of singlet formation, η R, which is defined as η R R R r nr R, in which,, hence r nr R R η R η τ R hus, the product of η and η R, and η *η R, is an important factor to dictate the what the degree of ADF process is, and the ratio of delayed fluorescence (DF) to prompt fluorescence (PF) is given by Φ Φ I I DF PF Φ Φ DF PF Φ Φ In this case, the PrDPhAc showed evident delayed fluorescence with η *η R = 67%, which means about two thirds of electron-generated excitons is bac-transferred to singlet states via up-conversion pathway because of its small ΔE. In other words, the density of triplet excitons was thus reduced obviously. With the disturbance of triplet oxygen molecule, by the way, the η *η R dropped drastically to ~6%, indicating only

11 a few triplet excitons can enter the singlet orbital because of the oxygen quenching effect. he Φ DF :Φ PF was estimated as :, indicating the singlet excitons increased by three times in ADF process. All the time-dependent data are summarized in able. able Data extracted from the transient characterization of PrDPhAc solution. PF (s - ) a DF (s - ) b τ PF (s) c τ DF (s) d (s - ) e (s - ) f * R (s - ) η *η R a) Delayed fluorescence rate constant; b) Prompt fluorescence rate constant; c) Delayed fluorescence lifetime; d) Prompt fluorescence lifetime; e) Fluorescence rate constant; f) Phosphorescence rate constant.

12 Ir O O C C PrDPhAc Ir(MDQ) (acac) C C C C HA-C CA mpypb APC Fig. 5 Molecular structures and representative energy level diagram of the materials.

13 Fig. 6 Current density voltage luminance (J-V-L) characteristics and EL spectra at 5 ma cm - for PrDPhAc based device. able 3 ummary of electroluminescence data for red OLED. Device V a CE b PE b ext b CIE c V cd A - lm W - % x, y R , , , , 0.39 a) Voltages at 00 cd m -. b) Efficiencies in the order of maximum and at 000 cd/m. c) Measured at 5 ma cm -. References X.-Y. Liu, F. Liang, L.-. Cui, X.-D. Yuan, Z.-Q. Jiang, L.-. Liao, Chem. Asian J., 05, 0, aagawa,.-y. Ku, K.-. Wong, C. Adachi, Chem. Commun., 0, 48,