Phosphorescent light-emitting electrochemical cell

Abstract

Due to the harvest of singlet and triplet excitons, highly-efficient phosphorescent polymer light-emitting diodes have been demonstrated. However, the driving voltage of these devices remains high because of the carrier trapping at the dopant sites. To achieve high power efficiency, a phosphorescent light-emitting electrochemical cell, which consists of bis [2-(2 ′ - benzothienyl )- pyridinato - N , C 3′ ] iridium ( acetylacetonate ) as the dopant, poly [9,9- bis (3,6- dioxaheptyl )- fluorene -2,7- diyl ] as the host polymer, and lithium trifluoromethane sulfonate has been demonstrated in this letter. The turn-on voltage for light emission was as low as the band gap of the host material (2.8 eV). Compared with the light-emitting diode with a similar device structure, a sixfold enhancement in power efficiency has been achieved.