Lowering the driving voltage and improving the luminance of blue fluorescent organic light-emitting devices by thermal annealing a hole injection layer of pentacene

Gao Jian^{1, 2, 3}, Yu Qian-Qian^{1, 2, 3}, Zhang Juan^{1, 2, 3}, Liu Yang^{1, 2, 3}, Jia Ruo-Fei^{1, 2, 3}, Han Jun^{1, 2, 3}, Wu Xiao-Ming^{1, 2, 3, †}, Hua Yu-Lin^{1, 2, 3, ‡}, Yin Shou-Gen^{1, 2, 3, §}

(color online) The EL characteristics of devices 1–5: (a) current density–luminance–voltage characteristics, (b) current efficiency–power efficiency–current density characteristics.