Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, 1 Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan, Republic of China.
Department of Chemistry, University of California, Riverside, Riverside, CA, 92506, USA.
Adv Mater. 2018 Dec;30(50):e1804850. doi: 10.1002/adma.201804850. Epub 2018 Oct 11.
Solid-state triplet-triplet annihilation upconversion (TTAUC) blue emission in an electroluminescence device (i.e., an organic light-emitting diode (OLED)) is demonstrated. A conventional green fluorophore, tris-(8-hydroxyquinoline)aluminum (Alq ), is employed as the sensitizer that generates 75% triplet under electrical pumping for the blue triplet-triplet annihilation emitter, 9,10-bis(2'-naphthyl) anthracene (ADN), with the heterojunction bilayer structure. The operation lifetime is elongated both for ADN blue (4.1x) and Alq green (34.8%) emission due to efficient use of excitons and separation of recombination and emission zone. To reduce the singlet quenching (SQ) of blue TTAUC signal by the Alq sensitizer with lower bandgap, 1-(2,5-dimethyl-4-(1-pyrenyl)phenyl)pyrene (DMPPP) is inserted between the Alq and ADN as a triplet-diffusion-and-singlet-blocking layer. DMPPP exhibits triplet energy close to Alq and higher than ADN, as well as higher singlet energy than both Alq and ADN. It allows triplet diffusion from Alq to ADN, but blocks the SQ of the blue TTAUC signal by Alq . 86.1% intrinsic efficiency of TTAUC is demonstrated in this trilayer (Alq /DMPPP/ADN) OLED.
固态三重态-三重态湮灭上转换（TTAUC）蓝色发射在电致发光器件（即有机发光二极管（OLED））中得到证明。传统的绿色荧光团，三（8-羟基喹啉）铝（Alq ）被用作敏化剂，在电泵浦下产生 75％的三重态，用于蓝色三重态-三重态湮灭发射器 9,10-双（2'-萘基）蒽（ADN），采用异质结双层结构。由于激子的有效利用和复合区与发射区的分离，ADN 蓝色（4.1x）和 Alq 绿色（34.8％）发射的工作寿命都延长了。为了降低带隙较低的 Alq 敏化剂对蓝色 TTAUC 信号的单重态猝灭（SQ），在 Alq 和 ADN 之间插入 1-(2,5-二甲基-4-(1-芘基)苯基)芘（DMPPP）作为三重态扩散和单重态阻挡层。DMPPP 表现出与 Alq 接近且高于 ADN 的三重态能量，以及高于 Alq 和 ADN 的单重态能量。它允许三重态从 Alq 扩散到 ADN，但通过 Alq 阻挡蓝色 TTAUC 信号的 SQ。在这种三层（Alq / DMPPP / ADN）OLED 中证明了 86.1％的 TTAUC 固有效率。
