Multicolor fluorescence and electroluminescence of an ICT-type organic solid tuned by modulating the accepting nature of the central core

Abstract

A donor-acceptor-donor (D-A-D) molecule di(triphenylamine)-thiazolothiazole 1 has been employed in which the central Lewis-basic nitrogen atoms prompt it to be responsive to strong acids in both solution and solid states. As a result, the electron-accepting strength and intramolecular charge transfer (ICT) character can be controllably enhanced which make the emission band of 1 sequentially red-shift. The green luminescent solids (524 nm) can be smoothly transferred into yellow (576 nm), red (640 nm), and near infrared (739 nm) emissive states with a huge Dl em of 215 nm after being evaporated by HCl, TFA, and Lewis acid BBr 3 , respectively. Taking advantage of the smart sensitivity of 1 to acids, we prepared thermal-evaporated OLEDs based on the neutral and protonated species for the first time and achieved multicolor electroluminescence (EL) with very high brightness and moderate current efficiency. Thus, multicolor photoluminescence and thermally evaporated electroluminescence have been firstly realized based on a single organic chromophore, to the best of our knowledge.

Single‐Molecular White‐Light Emitters and Their Potential WOLED Applications

“…Another example for the WOLED based on protonated molecule is described as follows. As mentioned before, the protonation of blue fluorophore in solid acid matrix promotes the emission of long wavelength by changing the ability of electron donation or acceptance to facilitate the energy transfer . Zhang and co‐workers developed WOLEDs by doping 0.1 wt% N ‐heterocyclic compounds 91 and 92 into solid acid (camphorsulfonic acid, CSA) with the device structure of ITO/NPB (40 nm)/TcTa (5 nm)/emitters:CSA (0.1 wt%, 15 nm)/bis[2‐(2‐hydroxyphenyl)‐pyridine]beryllium (Bepp 2 , 45 nm)/LiF (1 nm)/Al (100 nm).…”

Electroluminescence from colloidal semiconductor CdSe nanoplatelets in hybrid organic–inorganic light emitting diode

“…Observed peak is red-shifted with respect to TAZ photoluminescence maximum (λ = 384 nm) and blue-shifted with respect to TPD photoluminescence maximum (λ = 422 nm). We conclude that this additional EL peak corresponds to TAZ rather than TPD as red shifts of emission maxima are specific to electroluminescence compared with photoluminescence [22].…”

Reprint of: “AIE luminogen functionalized mesoporous silica nanoparticles as efficient fluorescent sensor for explosives detection in water”

“…This phenomenon can be explained based on the following: when the reaction proceeds, the hydrogen of the immobilized NH 2 on the surface of amine-modified MSNs may be dually substituted by fluorophores as the AIE molecules loading increased, leading to the donor segment of NH 2 changed to NHR, NR 2 or even acceptor segment NR 3 + . As is known, the attachment of an acceptor onto the TPE core offers a pull-push effect to the obtained molecules, thereby it is possible that this results in an intramolecular charge-transfer (ICT) process, which makes the emission bands of FMSNs sequentially red-shift [35,36]. On the other hand, the ratio of NH 2 -/OH-groups may be also responsible for the red shift of the emission bands of FMSNs, for TPE-MB can coordinate to OH-groups with formation of -HÁ Á ÁO-bonds, which will affect the orientation of TPE-MB in the channel [37].…”