Self-Assembled All-Conjugated Block Copolymer as an Effective Hole Conductor for Solid-State Dye-Sensitized Solar Cells

Abstract

An all-conjugated diblock copolymer, poly(2,5-dihexyloxy-p-phenylene)-b-poly(3-hexylthiophene) (PPP-b-P3HT), was synthesized and applied as a hole transport material (HTM) for the fabrication of solid-state dye-sensitized solar cells (ss-DSCs). This copolymer is characterized by an enhanced crystallinity, enabling its P3HT component to self-organize into interpenetrated and long-range-ordered crystalline fibrils upon spin-drying and ultimately endowing itself to have a faster hole mobility than that of the parent P3HT homopolymer. Transient photovoltage measurements indicate that the photovoltaic cell based on PPP-b-P3HT as the HTM has a longer electron lifetime than that of the reference device based on P3HT homopolymer. Moreover, comparing the two ss-DSCs in terms of the electrochemical impedance spectra reveals that the electron density in the TiO2 conduction band is substantially higher in the PPP-b-P3HT device than in the P3HT cell. Above observations suggest that the PPP block facilitates an intimate contact between the copolymer and dye molecules absorbed on the nanoporous TiO2 layer, which significantly enhances the performance of the resulting device. Consequently, the PPP-b-P3HT ss-DSC exhibits a promising power conversion efficiency of 4.65%. This study demonstrates that conjugated block copolymers can function as superior HTMs of highly efficient ss-DSCs.

Enhanced Hydrogen Evolution in the Presence of Plasmonic Au-Photo-Sensitized g-C3N4 with an Extended Absorption Spectrum from 460 to 640 nm

“…[43, 44] To gain insight into the interfacial resistance of the samples, EIS measurements were carried out at open-circuit voltages and in the dark. The Nyquist plots of all the samples are shown in Fig 8.…”

Dye-sensitized solar cells strike back

“…Wang et al investigated the properties of a pre-polymerized block copolymer of poly(3-hexylthiophene) and poly(2,5-dihexy- p -phenylene), and found that a PPP- b -P3HT-based solar cell achieved a V OC of 810 mV, J SC of 8.81 mA cm −2 , FF of 65% and PCE of 4.65%. 476 …”

“…475 Wang et al investigated the properties of a pre-polymerized block copolymer of poly(3-hexylthiophene) and poly(2,5-dihexyp-phenylene), and found that a PPP-b-P3HT-based solar cell achieved a V OC of 810 mV, J SC of 8.81 mA cm À2 , FF of 65% and PCE of 4.65%. 476 Liu et al investigated the performance of P3HT with two different dyes. When sensitised with BzTCA, solar cells achieved a V OC of 880 mV, J SC of 8.22 mA cm À2 , FF of 44% and PCE of 3.21%, demonstrating that organic dyes are better suited to operate with polymeric HTMs.…”

The researcher's guide to solid-state dye-sensitized solar cells

“…Wang and coworkers explored the properties of a prepolymerized block copolymer of poly(2,5-dihexyloxy-p-phenylene), PPP and poly(3-hexylthiophene), P3HT. 268 The PPP block helped the PPP-b-P3HT copolymer to self-organize in crystalline domains, which increased the hole mobility of the copolymer significantly (8.5 Â 10 À4 cm 2 V À1 s À1 ) compared to the P3HT homopolymer (1.9 Â 10 À4 cm 2 V À1 s À1 ) and, as the authors claimed, provided a more intimate contact with the CYC-B11 dye. The pore filling proved to be similar for both copolymer and P3HT but, thanks to the higher hole mobility and better contact with the dye, the PPP-b-P3TH-based solar cell achieved a V OC of 810 mV, J SC of 8.81 mA cm À2 , FF of 0.65 and PCE of 4.65%; while those employing P3HT could only display a V OC of 750 mV, J SC of 7.71 mA cm À2 , FF of 0.61 and PCE of 3.53%.…”