Approach to Fast Screen the Formation of an Exciplex

Abstract

Exciplex formation could be confirmed through photoluminescence (PL) measurement of films consisting of both hole transport material (HTM) and electron transport material (ETM) or by measuring the electroluminescence (EL) of organic light-emitting diodes (OLEDs) with an HTM:ETM mixed emitting layer (EML). However, preparation for solid films or OLEDs is time-consuming, thus reducing the effective identification of exciplex systems in broad material combinations. This study proposes a fast-screening method for exciplex formation by measuring PL spectra in a relatively high polar solvent. Several HTM:ETM combinations were used to assess the feasibility of the proposed fastscreening method. The exciplex was further confirmed by phosphorescence as well as transient PL decay. In addition, pure exciplex OLEDs with an HTM:ETM mixed EML exhibited EL spectra akin to their corresponding PL spectra measured in a high polar solvent, verifying exciplex formation. These results demonstrated that our proposed PL measurement in a high polar solvent could effectively accelerate the screening for exciplex formation, thereby boosting the rapid development of exciplex research.

Harnessing bipolar acceptors for highly efficient exciplex-forming systems

“…25,35,36 A fastscreening method was introduced to investigate exciplex formation by measuring the PL spectra of the D:A blends in a relatively high polarity solvent. 37 Consequently, four D : A (1 : 1) blended samples, TAPC:CzT2.1, TCTA:CzT2.1, TAPC:CzT2.2, and TCTA:CzT2.2, were prepared and denoted as blend A1, A2, B1, and B2, respectively. The donor and acceptor materials were initially dissolved in tetrahydrofuran (THF), and then deionized (DI) water was added to the solution to give the colloidal solution.…”

New Exciplex‐Forming Co‐Host System and Thienothiadazole‐based Fluorescent Emitter for High‐Efficiency and Promising Stability Near‐Infrared OLED

“…Apart from serving as an emitting layer (EML), exciplex is also applicable as a co-host for conventional fluorescent materials with high photoluminescence quantum yields (PLQYs) to give high-efficiency OLED. [20][21][22][23][24][25] Thus, the extension of emission wavelengths to NIR region can thus be reasonably achieved through fast Förster resonance energy transfer (FRET) processes. For example, Chou and coworker reported a NIR OLED with EL λ max of 710 nm and EQE up to 6.6% with an EML comprising a tailor-made NIR emitter NOz-t-TPA doped in Tris-PCz:CN-T2T exciplex co-host.…”

A Method to Realize Efficient Deep-Red Phosphorescent OLEDs with a Broad Spectral Profile and Low Operating Voltages

“…To avoid the time-consuming traditional method of confirming exciplex formation, our previous study proposed a method to fast-screen exciplex formation by observing whether the mixture of the selected HTM and ETM shine under excitation in relatively high polar solvents [ 12 ]. 4,4′,4″-tris(carbazol-9-yl)triphenylamine (TCTA) was chosen as the donor to blend with two commonly used ETMs [ 13 ], bis(10-hydroxybenzo[h]quinolinato)beryllium (Bebq2) or 3′,3‴,3‴″-(1,3,5-triazine-2,4,6-triyl)tris(([1,1′-biphenyl]-3-carbonitrile)) (CN-T2T) [ 14 , 15 ], for the exciplex fast-screening.…”