New perylene diimide derivatives: stable red emission, adjustable property from ACQ to AIE, and good device performance with an EQE value of 4.93%

Perylene diimide(PDI) derivatives, due to their special opto-electronic property, have been successfully utilized in organic field-effect transistor(OFET), solar cells, and as non-fullerene acceptor and others,while few cases in organic light-emitting diodes(OLEDs). In this work, six perylene bisimide-based red emitters, N,N''-bis(2-decyltetradecyl)-1-([1,1':3',1''-terphenyl]-5'-yl)perylene-3,4,9,10-diimide(STPH),N,N'-bis(2-decyltetradecyl)-1,7-bis([1,1':3',1''-terphenyl]-5'-yl)perylene-3,4,9,10-diimide(DTPH), N,N''-bis(2-decyltetradecyl)-1-(5'-phenyl-[1,1':3',1''-terphenyl]-4-yl)perylene-3,4,9,10-diimide(STRPH), N,N0-bis(2-decyltetradecyl)-1,7-bis(5'-phenyl-[1,1':3',1''-terphenyl]-4-yl)perylene-3,4,9,10-diimide(DTRPH),N,N0-bis(2-decyltetradecyl)-1-(4-(2,2-diphenylvinyl)phenyl)perylene-3,4,9,10-diimide(STTPE) and N,N'-bis(2-decyltetradecyl)-1,7-bis(4-(2,2-diphenylvinyl)phenyl)perylene-3,4,9,10-diimide(DTTPE), with the excellent chemical, thermal and photo-chemical stability, are synthesized through the convenient Suzuki coupling reaction, in which, the fluorescent properties can be modified easily from ACQ to AIE by just simply changing the bulky volume of the introduced aromatic substituents. After being fabricated into organic light-emitting diodes, STRPH exhibits the best performance with the maximum luminescence, power efficiency, current efficiency and external quantum efficiency of 1,948 cd m^(-2), 2.04 lm W^(-1), 5.85 cd A^(-1), 4.93% at Commission Internationale de L'Eclairage(CIE) coordinates of(0.56, 0.34),as the result of the high efficient energy transfer and good energy match achieved in the device.

The initial attempt to reveal the emission processes of both mechanoluminescence and room temperature phosphorescence with the aid of circular dichroism in solid state

A phenothiazine derivative PtzChol containing non-conjugated chiral cholesterol group was designed and synthesized. By analyzing the single crystal structure of PtzChol carefully, coupled with the circular dichroism(CD) signals before and after grinding, it was found that the introduction of cholesterol produced a positive effect on the production of chiral space group, on mechanoluminescence(ML) and room temperature phosphorescence(RTP), and throughout the entire light-emitting process, the CD signal could well reflect the changes of molecular arrangement.

Progress of pyrene-based organic semiconductor in organic field effect transistors

Thanks to the pure blue emitting, high planarity, electron rich and ease of chemical modification, pyrene has been thoroughly investigated for applications in organic electronics such as organic light emitting diodes(OLEDs), organic field effect transistors(OFETs), and organic solar cells(OSCs). Especially, great progresses have been made of pyrene-based organic semiconductors for OFETs in past decades. Due to the difference of molecular structure, pyrene-based organic semiconductors are divided into three categories, pyrene as terminal group, pyrene as center core and fused pyrene derivatives. This minireview gives a brief introduction of the structure-property relationship and application in OFETs about most of pyrene-based semiconducting materials since 2006,illustrating that pyrene is a good building block to construct semiconductors with superior transport property for OFETs. Finally, we provide a summary concerning the methodology to improve the transport property of the pyrene-based semiconducting materials as well as an outlook.

Utilizing Electroplex Emission to Achieve External Quantum Efficiency up to 18.1% in Nondoped Blue OLED

For the first time,electroplex emission is utilized to enhance the performance of nondoped blue organic light-emitting diodes(OLEDs).By decorating the twisted blue-emitting platform and adjusting the electronic structure,three molecules of 3Cz-Ph-CN,3Cz-mPh-CN,and 3Ph-Cz-CN with a donor-acceptor structure are synthesized and investigated.When external voltage is applied,electroplex emission,which contributes to the emission performance of OLED,can be realized at the interface between the emitting layer and the electron-transporting layer.Accordingly,high external quantum efficiency of 18.1%can be achieved,while the emission wavelength of the device can be controlled in the blue region.Our results provide the possibility to enhance the performance of OLED through electroplex emission,in addition to the generally investigated thermally activated delayed fluorescence(TADF).Excitedly,when 3Ph-Cz-CN is used as host material in orange-emitting phosphorous OLEDs(PO-01 as the dopant),unprecedented high external quantum efficiency of 27.4%can also be achieved.

Precise Regulation of Distance between Associated Pyrene Units and Control of Emission Energy and Kinetics in Solid State

Many approaches have been explored to tune emission behaviors of organic luminogens.However,precise regulation of distances in dimers is seldom reported.Here,four pyrene derivatives are presented,and we precisely regulate the distance between pyrene units of X2P.Its crystal manifests unusual deep-blue excimer emission at 424 nm,while the crystal of X1P with only one pyrene unit for each molecule gives sky-blue emission with a maximum emission peak at 475 nm.