Hierarchically Assembled Counter Electrode for Fiber Solar Cell Showing Record Power Conversion Efficiency

Abstract

Fiber solar cells have attracted significant interest as a promising wearable power supply solution for their merits of high flexibility, lightweight, and good compatibility with textile configuration and weaving process. However, because of the limited ion diffusion and charge transfer in the fiber counter electrode, the poor photovoltaic performances have long been one obstacle to hinder their real applications. Herein, in mimicking the efficient mass transport and exchange through the vascular tissue of plants like pine needle, a hierarchically assembled carbon nanotube (HCNT) fiber counter electrode is fabricated by a scalable process. The designed hierarchically aligned channels with large sizes of micrometers and small sizes of tens of nanometers in the HCNT fiber offers high‐flux pathways for rapid ion diffusion and abundant active area for charge transport, thus endowing the fiber dye‐sensitized solar cell with a record power conversion efficiency of 11.94%. By weaving such fiber solar cells in a scalable way, a flexible and breathable large photovoltaic textile (17 cm × 22 cm) is made to present a power output of 22.7 mW. These fiber solar cells are further integrated with fiber lithium‐ion batteries to efficiently power wearable electronics.

Advances and Future Prospects of Wearable Textile‐ and Fiber‐Based Solar Cells

“…These DSSCs can be further woven into flexible power fabrics that can withstand several tensile deformations (Figure 14h), for instance, bending and twisting, to efficiently and consistently power a pedometer under outdoor sunlight (Figure 14i). By simulating the effective mass transport and exchange of vascular tissues in plants such as pine needles, Kang et al [ 47 ] recently fabricated a hierarchically assembled CNT (HCNT) fiber counter electrode using a scalable technology (Figure 14j). The layered channels as large as microns and as small as tens of nanometers designed in HCNT fibers facilitated ion diffusion and charge transfer and improved the effective area of electrochemical response such that the corresponding FDSSCs demonstrated PCEs of 11.94%.…”

“…Copyright 2018, Royal Society of Chemistry; j) Hierarchically assembled C nanotube (HCNT) fiber counter electrode; and k) Schematic of an integrated wearable device with a health monitoring system and display. Reproduced with permission [47]. Copyright 2022, Wiley-VCH.…”

Performance enhancement strategies of fibrous solar cells for wearable hybrid energy systems

“…6d). 135 The electrode was prepared by using a series of techniques including chemical vapor deposition, twist treatment and Pt NP deposition. The introduction of rich micro- and nanochannels effectively promoted ion diffusion and charge transfer and improved the effective area of electrochemical reactions (Fig.…”

“…For example, Kang et al produced a flexible and breathable photovoltaic textile through an expandable manufacturing process. 135 In this design, FDSSCs were integrated with fibrous lithium-ion batteries (FLIBs), and this system could store the converted energy from FDSSCs into FLIBs in time for a stable power output (Fig. 15a).…”

Designing Reflective Hybrid Counter Electrode for Fiber Dye‐Sensitized Solar Cell with Record Efficiency

“…[5][6][7] To this end, fiber solar cells with advantages of flexibility and light weight have been widely explored to produce textiles as promising power systems. [8][9][10][11][12] Although extensive efforts in the synthesis DOI: 10.1002/adfm.202306742 of novel functional materials, [13][14][15] optimization of device structures, [16] and design of stable interfaces between active layers and substrates, [17] the present fiber solar cells show relatively low power conversion efficiencies (PCEs) due to the difficulty of high-quality device fabrication on curved fibers, which has severely limited their further development, particularly for real applications in wearables. [18][19][20] Another possible solution to this bottleneck problem lies in the strategy to take the unique advantage of fiber solar cells in comparison to their planar counterparts, i.e., effectively absorbing light from 360°directions.…”