Controlled Sulfidation Approach for Copper Sulfide–Carbon Hybrid as an Effective Counter Electrode in Quantum-Dot-Sensitized Solar Cells

Abstract

Because of their good conductivities and high catalytic activities, carbon materials and copper sulfides have been individually and jointly used as counter electrodes in quantum-dot-sensitized solar cells (QDSCs). However, obtaining a combination of high conversion efficiency and stability is still challenging. In this work, we present a facile method for fabricating Cu 1.8 S−C hybrid counter electrodes through the sulfidation of a copper−carbon composite synthesized by grinding a mixture of organic binder, commercial copper powder, and carbon material containing activated carbon and carbon black in a designed mass ratio. The assembled CdSeTe-sensitized QDSCs achieved a high PCE of 8.40%, larger than that of pure carbon (5.25%) and comparable to that of conventional Cu x S/brass-based QDSCs (8.44%). Significantly, the devices based on Cu 1.8 S−C showed excellent stability. The improved performance is mainly attributed to the good conductivity and stability of carbon and the high catalytic activity of Cu 1.8 S.

Quantum dot-sensitized solar cells

“…To overcome the stability issue induced by brass foil based CEs, several groups developed novel CEs on FTO substrate to improve the stability of the cell device. 342,349,398,399,411,495 For example, Meng's group prepared two kinds of composite CEs, PbS/carbon black and CuInS2/carbon black on FTO substrate. 398,399 It was proposed that the framework of carbon black used in the composite CE together with PVDF binder provided good physical contact between nanoparticles and the FTO substrate and therefore can improve the long-term stability of the CE.…”

High‐performance counter electrode based on nitrogen‐doped porous carbon nanoribbons for quantum dot‐sensitized solar cells

“…R 1 is mainly related to the contact degree between Ti mesh substrate and carbon materials. The R 1 of NPCN electrode is lower than that of NCNT electrode, demonstrating the better contact between Ti mesh and NPCNs 19,37 . R ct is widely used to characterize the electrocatalytic ability of the electrode materials.…”

“…Figure 7A shows Nyquist plots obtained over frequency range of 10 6 to 1 Hz for the sandwich cells with PbS, NCNT, and NPCN electrodes. In the Nyquist plots of the cells assembled with NCNT and NPCN electrodes, the high-frequency semicircle (between 10 6 and 10 3 Hz) is assigned to the electric response of the solid-solid contact between the carbon materials and Ti mesh, [37][38][39] and the low-frequency semicircle (between 10 3 and 1 Hz) is assigned to the interfacial charge-transfer process (consisting of the constant phase element [CPE] and charge-transfer resistance [R ct ]). Figure 7b displays the equivalent circuit for fitting Nyquist plots of the devices assembled with NCNT and NPCN electrodes.…”

CNT@rGO@MoCuSe Composite as an Efficient Counter Electrode for Quantum Dot-Sensitized Solar Cells

“…Fabrication of CdSeTe Sensitized QDSSCs. The synthesis of the CdSeTe sensitizer, deposition of QDs on the TiO 2 film, and deposition of ZnS and SiO 2 layers were carried out using the literature methods; 18,19 the active area of the TiO 2 on fluorine-doped tin oxide (FTO) substrate was 0.25 cm 2 . The QDSSC devices were constructed by assembling the CNT@rGO@MoCuSe CE and sensitized TiO 2 photoanode with a sealant (SX 1170-60, Solaronix) at 100 °C; the devices were then filled with a polysulfide electrolyte, which consisted of 1 M Na 2 S, 2 M S, and 0.1 M KCl in methanol/water (7:3).…”