Long‐Persistent Luminescence from an Exciplex‐Based Organic Light‐Emitting Diode

Abstract

Organic long‐persistent luminescent systems (OLPLs) exhibiting long‐lasting emission after photoexcitation consist of organic electron donors and acceptors, that are widely used in organic light‐emitting diodes (OLEDs). Although OLPLs and OLEDs include very similar excitonic processes, long‐lasting emission has never been observed in OLEDs. This study confirms the presence of long‐persistent luminescence (LPL) under electrical excitation.

Photoluminescence and electrochemiluminescence of thermally activated delayed fluorescence (TADF) emitters containing diphenylphosphine chalcogenide-substituted carbazole donors

“…113 More recently, this OLPL system has been used in an OLED to achieve organic long-persistent electroluminescence (OLEL). [114][115] Unfortunately, solution and solid state emission delays of the system were not investigated on time scales smaller than 1 s, thereby limiting comparisons with the 2CzPN derivatives. However, OLPL and OLEL are both emitted from an exciplex state and therefore the emission was found to be both concentration dependent and layer-thickness dependent.…”

Organic Long-Persistent Luminescence from a Single-Component Aggregate

“…Long-persistent luminescence (LPL) describes the phenomenon where luminescence is observed for extended durations after the cessation of an excitation source. , The ability to store excitation energy before subsequently releasing it has caught the attention of many for its invaluable potential. − Perhaps one of the most direct applications of this property is to target the global climate crisis fueled by the world’s combustion of fossil fuels through electricity-free lighting or enhancing solar cells and up-conversion materials. , LPL materials have also been exploited for biomedical sciences as deep-tissue imaging agents that do not require continuous excitation. − In doing so, this bypasses the need to locate the dyes within the organism postinjection as well as exciting the dyes through the organism’s tissues. ,− …”

Long-Persistent Luminescence from Double Self-Defect States in Undoped Cs3In2Cl9 Nanocrystals for Bioimaging and Display Technologies

“…The earliest report of organic LPL from solid crystalline tetraphenylmethane and tetraphenylsilane derivatives can be dated back to 1930s . In the 1970s, strong LPL of triplet-state emission was observed. , There are various effective methods to prolong charge-transfer transition, such as engineering crystallization, , employing dopants, − and forming a complex of donors and acceptors. , However, some disadvantages still hinder the practical application of LPL organic molecules, for example, the limited stability due to high inevitable phase separation in small organic molecules and the quenching of triplet excitons by oxygen and moisture in polymer LPL molecules. − …”