522
Y. Ooyama
Fig. 14.42 Chemical structures of diketopyrrolopyrrole (DPP) dye sensitizers DPP-Br and
DPPCN 2 and an An–D–π–A DPP dye sensitizer DPP-1 for NiO DSSCs
14.5.3 Diketopyrrolopyrrole Dyes
Diketopyrrolopyrrole (DPP) with electron-withdrawing ability shows a strong
photoabsorption band around 500 nm and particularly high photostability. DPPbased dye sensitizers for p-type NIO DSSCs have been developed, and their photovoltaic performances have been investigated (Fig. 14.42). Odobel et al. developed
DPP-based dyes with thienyl carboxylic acid as an anchoring group and with either
bromine (DPP-Br) or dicyano vinyl (DPPCN 2 ). DPP-Br and DPPCN 2 showed
an intense photoabsorption band at 490 nm (ε = 16900 M
−1 cm
−1 ) and 508 nm
(ε = 21400 M
−1 cm
−1 ), respectively, which is ascribed to a DPP-centered π–π*
electron transition. The η values of the p-type NiO DSSCs based on DPP-Br and
DPPCN 2 were 0.03% and 0.07%, respectively (Favereau et al. 2013). On the other
hand, Hammarström and co-workers reported that the NiO DSSCs based on an An–
D–π–A DPP dye DPP-1 with two carboxyl groups on diphenylamine yielded an η
value of 0.063% with a J sc value of 1.89 mA cm
−2 , a V oc value of 100 mV, and a ff
value of 0.33, and a maximum IPCE value of 25% (Farré et al. 2016).
14.5.4 Squaraine Dyes
Lin et al. developed NIR squaraine dyes p-SQ1 and p-SQ2 with one and two
anchoring groups as sensitizers for p-type NiO DSSCs (Fig. 14.43) (Chang et al.
Y. Ooyama
Fig. 14.42 Chemical structures of diketopyrrolopyrrole (DPP) dye sensitizers DPP-Br and
DPPCN 2 and an An–D–π–A DPP dye sensitizer DPP-1 for NiO DSSCs
14.5.3 Diketopyrrolopyrrole Dyes
Diketopyrrolopyrrole (DPP) with electron-withdrawing ability shows a strong
photoabsorption band around 500 nm and particularly high photostability. DPPbased dye sensitizers for p-type NIO DSSCs have been developed, and their photovoltaic performances have been investigated (Fig. 14.42). Odobel et al. developed
DPP-based dyes with thienyl carboxylic acid as an anchoring group and with either
bromine (DPP-Br) or dicyano vinyl (DPPCN 2 ). DPP-Br and DPPCN 2 showed
an intense photoabsorption band at 490 nm (ε = 16900 M
−1 cm
−1 ) and 508 nm
(ε = 21400 M
−1 cm
−1 ), respectively, which is ascribed to a DPP-centered π–π*
electron transition. The η values of the p-type NiO DSSCs based on DPP-Br and
DPPCN 2 were 0.03% and 0.07%, respectively (Favereau et al. 2013). On the other
hand, Hammarström and co-workers reported that the NiO DSSCs based on an An–
D–π–A DPP dye DPP-1 with two carboxyl groups on diphenylamine yielded an η
value of 0.063% with a J sc value of 1.89 mA cm
−2 , a V oc value of 100 mV, and a ff
value of 0.33, and a maximum IPCE value of 25% (Farré et al. 2016).
14.5.4 Squaraine Dyes
Lin et al. developed NIR squaraine dyes p-SQ1 and p-SQ2 with one and two
anchoring groups as sensitizers for p-type NiO DSSCs (Fig. 14.43) (Chang et al.