Tuning the Electrical and Optical Properties of Diketopyrrolopyrrole Complexes for Panchromatic Dye‐Sensitized Solar Cells

Abstract

A series of metal-free organic dyes that were bridged by a diketopyrrolopyrrole moiety and were composed of indoline and triphenylamine as donor groups and furan and benzene as conjugated spacer groups were designed and synthesized for use in dye-sensitized solar cells (DSCs). The photophysical properties, electrochemical properties, and performance of the DSCs were related to the structure of their corresponding dyes. Their absorption spectra broadened upon the introduction of the indoline and heterocyclic furan moieties through fine-tuning of their molecular configuration. The overall conversion efficiencies of DSCs that were based on these dyes ranged from 5.14-6.53%. Among the four dyes that were tested, indoline-based ID01 and ID02 showed higher efficiencies (6.35% and 6.53%) as a result of their improved light-harvesting efficiency and larger electron driving force. The ID01 dye, which contained an indoline moiety as an electron donor and a furan group as a π-conjugated linker, showed an excellent monochromatic incident-photon-to-current-conversion efficiency (IPCE) spectrum (350-650 nm) with a maximum value of 78% in the high plateau region and an onset value close to 800 nm. Intensity-modulated photovoltage spectroscopy (IMVS) and impedance spectroscopy (IS) revealed that dyes that contained benzene conjugation spacers suppressed the charge-recombination rate more efficiently than dyes that contained furan spacers, thereby resulting in improved photovoltage.

Highly efficient dye-sensitized solar cells: progress and future challenges

“…Fig. 7 (a) Molecular structures of the Ru-bpy sensitizers with p-conjugate system, N945H, 30 C101, 31 and C106, 35 (b) donor substituted, 42,78 and (c) tpy substituted black dye analogues. 43,44 comparing with those of black dye.…”

“…Practically, cyanoacrylic acid and its analogues, 59,60 rhodanines, 51,52,55,[61][62][63] and pyridines 64,65 are frequently used owing to their electron-withdrawing properties and coordinating features to the TiO 2 electrode. As p-spacer units, p-conjugated systems such as polyenes, 66-68 polyynes, [69][70][71] thiophenes, [72][73][74][75] furanes, [76][77][78] pyrroles, [79][80][81] fused thiophenes, [82][83][84][85] diketopyrrolopyrrole, [86][87][88] benzothiadiazole, 53,54,89,90 and benzotriazole 91,92 are incorporated into D-p-A dyes. In a D-p-A organic dye, the HOMO is mainly localized at the donor and the electron-rich pspacer part, and the LUMO is distributed on the acceptor part and the anchoring group.…”

Panchromatic dyes having diketopyrrolopyrrole and ethylenedioxythiophene applied to dye-sensitized solar cells

“…developed in this study were extended beyond 800 nm compared with those of 700 nm or below for most of DPP-dyes reported earlier [12,[18][19][20][21][22][23][24][25][26][27][28][29][30]. The band-edge extinction due to the introduction of EDOT unit in π-linkers is responsible, in part, for the panchromatic nature of DPP1-4.…”

“…DPP was originally developed as a commercially available industrial pigment for the application to car-paint pigments and polymeric organic photovoltaics [15][16][17], and is expected to have a strong light-harvesting ability. From this viewpoint, several DPP-containing D-A-π-A dyes have been synthesized [12,15,[18][19][20][21][22][23][24][25][26][27][28][29][30].…”

Novel metal complexes for D‐(A‐π‐A)2motif dye sensitizer: Synthesis and photovoltaic application

“…Recently, there are several types of electronwithdrawing units, such as benzothiadiazole (BTD), [13][14][15][16] benzotriazole (BTZ), [17][18][19] quinoxaline (Qu), [20][21][22][23] phthalimide, [24] and diketo-pyrrolopyrrole (DPP), [25][26][27] that have been systematically exploited as the auxiliary electron acceptor for the D-A-π-A structures. There is a trend to systematically add benzoxadiazole, benzothiadiazole, quinoxaline, and benzotriazole as an auxiliary electron acceptor to the D-π-A system, and test and theoretical calculation are performed.…”