Polyfluorenes containing 1.8-naphthalimide dye as endcapping groups

A series of polyfluorene derivatives endcapped by 0.1-2 mol% 1,8-naphthalimide dye were synthesized by Yamamoto coupling reaction. The resulting polymers show the promising electroluminescence (EL) performance with emission predominantly from the 1,8-naphthalimide unit due to energy transfer and charge trapping from polyfluorene backbone to 1,8-naphthalimide dye. Single-layer devices were fabricated with a device configuration of ITO/PEDOT/polymer/Ca/Al. Among all the devices tested, the device of NFP50 exhibited the current efficiency of 7.40 cd/A, the power efficiency of 2.89 lm/W and the maximum brightness of 19280 cd/m2, about 30 times more efficient than that of polyfluorene without endcapping groups.