The subject invention pertains to compositions of a probe comprising two pH-reversible forms, including the boron dipyrromethene (BODIPY) fluorescent form and the non-fluorescent leuco-BODIPY form, for use in confocal imaging methods of intracellular vesicles as well as extracellular vesicles that are present in conditioned culture medium and/or secreted by living cells, without inducing severe cytotoxicity.

An organic light emitting diode (OLED) including at least one emitting material layer (EML) disposed two electrodes and comprising triazine-based delayed fluorescent material and boron-dipyrromethene-based fluorescent material and an organic light emitting device including the OLED is disclosed. The triazine-based delayed fluorescent material and the boron-dipyrromethene-based fluorescent material may be included in an identical EML or in adjacently disposed EMLs. The OLED can lower its driving voltage and improve its luminous efficiency by adjusting energy levels of the delayed fluorescent material and the fluorescent material.

Provided are organometallic compounds. Also provided are formulations comprising these organometallic compounds. Further provided are OLEDs and related consumer products that utilize these organometallic compounds.