Approach to Fast Screen the Formation of an Exciplex

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 fast-screening 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.