We have fabricated highly efficient red phosphorescent organic light-emitting diodes (PHOLEDs) incorporating a bipolar host material, 2,7-bis(phenylsulfonyl)-9-[4-(N,N-diphenylamino)phenyl]-9-phenylfluorene (SAF), doped with 7 wt% tris(1-phenylisoquinolinolato-C2,N)iridium(III) [Ir(piq)3]. Attaching the electron-donating (p-type) triphenylamine group onto the electron-accepting (n-type) 2,7-bis(phenylsulfonyl)fluorene segment (through the C9 position of the fluorene unit) imparts SAF with good morphological stability, high triplet energy gap (ET), bipolar transporting ability, and matching energy levels with adjacent carrier-transporting layers. Consequently, the SAF-based red-PHOLED exhibited a very low turn-on voltage (2.4 V) and high electroluminescence efficiencies of 15.8% and 22.0 lm W−1, superior to those of the corresponding device incorporating a conventional host material, 4,4′-N,N′-dicarbazolbiphenyl (CBP; 3.2 V, 8.5%, and 8.4 lm W−1, respectively). At a practical brightness of 1000 cd m−2, the efficiencies of the SAF-based red-PHOLED remained high (13.1%, 14.4 lm W−1).
我们制造出了高效的红色
磷光有机发光二极管(PHOLED),其中包含一种双极主材料--2,7-双(苯磺酰基)-9-[4-(N,N-二苯基
氨基)苯基]-
9-苯基芴(
SAF),并掺杂了 7 wt%的三(
1-苯基异喹啉-C2,N)
铱(III)[Ir(piq)3]。将电子捐赠(p 型)
三苯胺基团连接到电子接受(n 型)2,7-双(苯磺酰基)
芴段(通过
芴单元的 C9 位置)使
SAF 具有良好的形态稳定性、高三重能隙(ET)、双极传输能力以及与相邻载流子传输层匹配的能级。因此,基于
SAF 的红光光致发光器件的开启电压非常低(2.4 V),电致发光效率高达 15.8% 和 22.0 lm W-1,优于采用传统宿主材料 4,4′-N,N′-二
咔唑联苯(CBP;分别为 3.2 V、8.5% 和 8.4 lm W-1)的相应器件。在实际亮度为 1000 cd m-2 时,基于
SAF 的红光光致发光二极管的效率仍然很高(13.1%,14.4 lm W-1)。