Both TRUCPL and threshold intensity measurements signify an increased concentration of triplets in the rubrene/DBP layer upon the introduction of TCA. Since TCA possesses a carboxylic acid group which has a strong affinity to bind to the surface of PbS QDs, we hypothesize that it behaves as an extractor/mediator ligand to aid in energy transfer to the annihilator in addition to reducing back ttransfer. Additionally, since triplet excitons in organic semiconductors are long-lived, the extraction of excitons by semiconducting ligands helps overcome the radiative and non-radiative losses that hinder the triplet transfer from PbS QDs without extractor ligands. Here, we postulate that the binding of TCA to PbS QDs increases the exciton extraction efficiency (φET1). Still, since the device improvements could originate from either improved exciton extraction efficiency or reduced BT, we undertook further investigations to better understand the full nature of the origins of the device improvement.