Solar Cell Application of 1D Heterostructure Based on Single-Walled CNT

Abstract

The experimental synthesis of one-dimensional (1D) van der Waals heterostructures, first introduced in 2020 [1], has attracted much research attention. Discussions upon this coaxial stack of different atomic layers are not only limited to synthesis and characteristics, but also extended to applications. Many unique properties of the 1D van der Waals heterostructures, such as the adjustable band gap, strong quenching of photoluminescence of MoS2 by inner single-walled CNT, enable this structure to be a potential active layer material for solar cells [2].For the synthesis of 1D van der Waals heterostructures, we first use dispersed high-purity semiconducting single-walled carbon nanotubes (s-SWCNT) solution obtained from Kataura group [3] as inner tube material. With an anodic aluminum oxide (AAO) membrane filter and HCl, we managed to fabricate a free-standing s-SWCNT film [4]. Then following our established CVD process [5], we are wrapping this inner s-SWCNT tube with an insulating boron nitride layer, and a semiconducting MoS2 layer. After that, the as-prepared 1D van der Waals heterostructures film will be utilized for solar cell fabrication.The solar cell is adopting an n-i-p structure, in the order of glass-ITO-SnO2-Active layer-Spiro-Au. After spin-coating and annealing SnO2 (electron transporting layer) onto ITO-patterned glass, the 1D van der Waals heterostructure film is laminated on the SnO2 layer. Spiro (hole transporting layer) will be then spin-coated onto the film. Finally, gold is vapor-deposited onto the device in a vacuum chamber, as the top electrode [6].Through photocurrent measurement of 1D van der Waals structure film using Esko film, a mixture of metallic-SWCNT and s-SWCNT, we found it is photosensitive with exposure to light and laser. The 1D van der Waals structure film using high-purity s-SWCNT is then expected to generate higher photocurrent, the experimental result will be updated in the future. By the IV measurement of the solar cell, we observed the photovoltaic effect of the device. Moreover, this new conceptual solar cell is believed to possess many advantages at the same time, such as flexibility, durability, non-toxicity, and sustainability [2]. However, further research on the choices of materials and optimizations of device parameters is still required in order to reach sufficient power conversion efficiency as a photovoltaic device.[1] R. Xiang et al., Science 367, 537–542 (2020)[2] R. Xiang et al., Natl Sci Open 1, 3 (2022)[3] J. Cui et al., ACS Appl. Nano Mater 2, 1, 343–350 (2019)[4] C. Zhang et al., ACS Nano 16, 11, 18630–18636 (2022)[5] M. Liu et al., ACS Nano 15, 5, 8418–8426 (2021)[6] J.-M. Choi et al, Adv. Funct. Mater. 32, 2204594 (2022)