@article { ISI:000448415300015,
	title = {Positional isomerism effect of spirobifluorene and terpyridine moieties of {\textquoteleft}{\textquoteleft}(A)(n)-D-(A)(n){\textquoteright}{\textquoteright} type electron transport materials for long-lived and highly efficient TADF-PhOLEDs},
	journal = {JOURNAL OF MATERIALS CHEMISTRY C},
	volume = {6},
	number = {38},
	year = {2018},
	month = {OCT 14},
	pages = {10276-10283},
	abstract = {Combining rigid twisted spirobifluorene with two strongly electron-withdrawing terpyridine moieties to form a {\textquoteleft}{\textquoteleft}(A)(n)-D-(A)(n)\&$\#$039;\&$\#$039; structure is an effective way to achieve electron transport materials (ETMs) with high triplet energy, suitable frontier orbital levels, excellent thermal stability and electrochemical stability for long-lived and highly efficient organic light-emitting diodes (OLEDs), 2,2\&$\#$039;-di([2,2\&$\#$039;:6\&$\#$039;,2 {\textquoteleft}\&$\#$039;-terpyridin]-4\&$\#$039;-yl)-9,9\&$\#$039;-spirobi[fluorene] (22-TPSF) and 2,7-di([2,2\&$\#$039;:6\&$\#$039;,2 {\textquoteleft}\&$\#$039;-terpyridin]-4\&$\#$039;-yl)-9,9\&$\#$039;-spirobifluorene (27-TPSF), both of which are better than the conventional ETM 1,3,5-tris(N-phenylbenzimidazol-2-yl-benzene (TPBi). In addition, the crystal packing mode in their single crystals undergoes a significant transformation from the sandwich arrangement of 22-TPSF into the brick wall arrangement of 27-TPSF, causing a big difference in electron transport mobility, which changes from 0.012 to 0.104 cm(2) V-1 s(-1) as calculated through density functional theory. This variation leads to a phenomenon where the 22-TPSF based devices display a lower maximum external quantum efficiency of 22.9\% and a shorter half-life (T-50) of 173925 hours at an initial luminance of 100 cd m(-2) than the 27-TPSF based devices. These findings highlight the great potential of the ETM structured as {\textquoteleft}{\textquoteleft}(A)(n)-D-(A)(n)\&$\#$039;\&$\#$039; using the terpyridine and spirobifluorene moieties; moreover, the positional isomerism effect allows remarkable tuning of the electron transport mobility and makes an obvious influence on OLED performance and lifetime.},
	issn = {2050-7526},
	doi = {10.1039/c8tc03796e},
	author = {Bian, Mengying and Wang, Yuanxun and Guo, Xuan and Lv, Fang and Chen, Zhijian and Lian Duan and Bian, Zuqiang and Liu, Zhiwei and Geng, Hua and Xiao, Lixin}
}
