Triplet–triplet annihilation (TTA) mechanism utilizing the conversion of low triplet energy excitons to generate singlet excitons has been successfully employed in realizing highly efficient fluorescent organic light‐emitting diodes (OLEDs). Herein, new anthracene‐based TTA molecules (TPNACN and TPBACN) are developed as deep‐blue emitters for high‐efficiency non‐doped TTA‐OLEDs. Their structural, physical, and photophysical properties are experimentally and theoretically investigated. These compounds in solid‐state exhibit different photophysical properties due to a discrepancy in the molecular packing. Particularly, in the crystal of TPNACN, anthracene moieties are arranged with dimeric π–π stacking, and the material shows a strong excimer emission in the deep‐blue region with ΦPL close to the ideal theoretical value. The non‐doped TTA‐OLED based on TPNACN attains a high maximum external quantum efficiency of 7.89% (6.63 cd A−1) with a low turn‐on voltage of 2.6 V, and displays deep‐blue emission with CIE coordinates of (0.146, 0.101). These results prove that a separated dimeric π‐stacked molecular alignment of anthracene enhances not only the fluorescence efficiency in the solid state but also the ratio of singlet exciton harvested by the TTA process in the device, bringing about excellent device electroluminescent properties. This can be a new tactic to designing new emissive materials for efficient OLED devices.
Perovskite solar cells (PSCs) have received high attention in the past few years due to their terrific photovoltaic performance and potentially low production cost. However, the use of hole transport materials (HTMs) with hygroscopic dopants, which cause the inevitable instability of device performance, has hampered commercialization. Herein, a dopant-free polymeric HTM with functional aromatic rings was used to optimize the HTM/perovskite interface and employed in a planar n-i-p configuration. Poly(1,4-(2,5-bis((2-butyloctyloxy)phenylene)-2,7-(5,5,10,10-tetrakis(4-hexylphenyl)-5,10-dihydro-s-indaceno[2,1b:6,5-b']dithiophene)) (IDTB) co-polymer constructed with indaceno[1,2-b:5,6-b']dithiophene and bis(alkyloxy)benzene units adopts an S•••O intramolecular bond linked ladder-like planar conjugated polymer backbone. Without any dopant, the hole mobility of IDTB is in the same order of magnitude as a doped 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-OMeTAD). Also, the hydrophobic nature of IDTB facilitated the long-term stability of the perovskite underneath. The unencapsulated PSC devices made of IDTB-based HTM achieved a power conversion efficiency of 19.38 % with a high moisture stability, retaining above 80 % of initial power conversion efficiency at 65 % relative humidity for more than 10 days. The superior passivation effect to perovskite surface made a hysteresis of 0.44 % was almost the least reported for regular planar undoped polymer HTM PSCs.
Herein, two new solution-processable HLCT fluorophores (CBzF and CBzFC) based on benzothiadiazole (Bz) derivatives were designed and synthesized (HLCT = hybridized local and charge transfer). Their optical and photophysical properties were experimentally and theoretically studied and verified by the solvatochromic effect and density functional theory calculations. The two molecules demonstrate high solubility, HLCT features, and an intense green fluorescence with solid-state photoluminescence quantum yields of 63-72 %. Both fluorophores are effectively applied as non-doped emitters for solution-processed double-layered OLEDs, which produce intense green emission colors with low turn-on voltages (3.0-3.2 V). Specifically, the CBzFC-based solution-processed device achieves a high maximum luminescence (24400 cd m À 2 ), high maximum efficiencies (EQE max = 5.59 %, CE max = 12.24 cd A À 1 , and PE max = 10.54 lm W À 1 ), and decent efficiency low-off.
Naphthothiadiazole derivatives with aggregation-induced emission enhancement exhibited a non-doped EL device emitted brilliant near infrared emission peaked at 754 nm with high EQE as high as 1.48%.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.