Controlling triplet–triplet upconversion and singlet-triplet annihilation in organic light-emitting diodes for injection lasing

Abstract Significant progress has recently been made in the field of organic solid-state lasers. However, achieving lasing action from semiconductors under electrical excitation remains challenging due to losses introduced by triplet excitons. Here, we report experimental and theoretical results that confirm a positive contribution excitons for electrically-driven via bimolecular triplet-triplet upconversion (TTU) mechanism. We study model fluorescent material, 9-(9-phenylcarbazole-3-yl)-10-(naphthalene-1-yl)anthracene, revealing TTU can lower threshold current densities required achieve injection. best performance, singlet-triplet annihilation (STA) must be simultaneously minimized. Hence, an strategy obtain high with low STA is demonstrated host-guest system coumarin 545T as guest laser dye. This amplified spontaneous emission 1.7 µJ cm ? 2 nanosecond optical pumping, more than three orders magnitude improvement J 50 light-emitting diodes compared reference blend.