Abstract
A new class of dibenzosuberene derivatives with diphenylamine and N,N-diphenylthiophen-2-amine as donor at C-3 and C-7 and with α-cyanoacrylic acid and different conjugated π-system units at C-5 were synthesized as five novel D-π-A-featured compound 4, 8 and 13 D-π-A-A-featured compound 22 and D-π-A-π-A-featured compound 26 for dye-sensitized solar cell applications. These five compounds whose maximum absorption wavelength were observed at 376 nm and 499 nm, respectively, and the molar absorption coefficient were observed at 26,300 M-1 cm-1 and 56,900 M-1 cm-1, respectively. The best device performance was D-π-A-π-A-featured compound 26, and it showed a conversion efficiency (η) of up to 3.28% (Voc = 633 mV, JSC = 6.78 mA/cm2, FF = 0.76) under AM 1.5 G conditions. And the best IPCE values achieved 54% within the 400 - 550 nm absorption range. Besides, we developed a new class of cis-stilbene/fluorene spiro hybrid systems with ambipolar organic fluorescent materials for organic light-emitting diodes applications. We utilized sp3-C of spiro center as the molecular bridge to suppress the donor–acceptor interactions by appending diphenylamine onto the C-3 and C-7 position and cyano group onto the C-2’ and C-7’ position for compound 32 (N2-STIF-CN2) and appending diphenylamine onto the C-2’ and C-7’ position and cyano group onto the C-3 and C-7 position for compound 34 (CN2-STIF-N2). We demonstrated red-emitting PhOLED using the compound 34 as the ambipolar host material and [Os(bpftz)2(PPhMe2)2, OS1] as red dopant (i.e., ITO/TAPC/CN2-STIF-N2:10% OS1/CN-STIF-CN/LiF/Al). This device showed a maximum current efficiency of 1.6 cd/A, power efficiency of 0.81 lm/W, EQE of 1.6%, and a maximum brightness of 15,400 cd/m2 at 1,000 cd/m2 with CIE color coordinates of (0.65, 0.35). We tried to use BANE and CBP as host material and the compound 32 and 34 as dopant (i.e., ITO/PEDOT:PSS/host : 5% dopant/TPBI/LiF/Al), but there was no thermally activated delayed fluorescence (TADF) observed in compound 32 and 34. The device with CBP as host material and compound 34 as dopant showed the best performance. The device emitted yellow light and showed a maximum current efficiency of 0.61 cd/A, power efficiency of 0.29 lm/W, and a maximum brightness of 858 cd/m2 at 20 mA/cm2 with CIE color coordinates of (0.50, 0.48).