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1 The migration of free electron–hole pairs in solar cells plays a vital role in the efficiency performance. 1–6 A primary requirement for a high-quality heterostructure solar cell is that the band gaps of both donor and acceptor materials should be in the range of roughly 1.2–1.6 eV. Different two-dimensional (2D) semiconductors combining van der Waals (vdW) via the vdW interaction have been reported as an efficient method for designing high-quality solar cells. Introduction Solar cells converting sunlight directly into electricity provide a new approach for the sustainable application of green and clean solar energy. Our present study paves the way for facilitating the potential application of MXenes as photovoltaic materials. In particular, Ti 2CO 2/Zr 2CO 2 and Ti 2CO 2/Hf 2CO 2 heterostructure solar cells deliver a very high power conversion efficiency of 22.74% and 19.56%, respectively. Furthermore, the photocurrents of Ti 2CO 2/Zr 2CO 2 and Ti 2CO 2/Hf 2CO 2 heterostructure solar cell devices are competitive with those of silicon devices. Moreover, the type-II nature of the heterostructures could induce effective electron–hole separation. Interestingly, the heterostructures have a moderate band gap of 1.22 eV and exhibit a noticeable absorbance coefficient of 10 5 cm −1 in the visible light region. The results highlight that Zr 2CO 2 (Hf 2CO 2) and Ti 2CO 2 are promising donor and acceptor materials, respectively.
In this paper, based on density functional theory calculations, we comprehensively evaluated 64 two-dimensional transition metal carbides (MXenes) to explore them as appropriate semiconductors for solar cells by material screening. Constructing heterostructure solar cells using donor and acceptor semiconductors has attracted global interest owing to their high power conversion efficiency.