Preparation and Growth Mechanism of Pyramid-Shaped Cu2ZnSnS4 Monocrystal and the Simulation of Its Monograin Layer Solar Cells

The Cu₂ZnSnS₄(CZTS) monocrystal as an important component of the optical absorption layer in monograin layer solar cells, has excellent crystallization characteristics and adjustable photogenerated carrier concentration. The shape of the CZTS monocrystal directly affects the utilization of incident light and the contact area during the preparation of the back electrode when they are densely packed to form a single-layer absorption layer. Herein, a kesterite-phase pyramid-shaped CZTS monocrystal prepared by the molten salt method is reported, which can improve the efficiency of incident light utilization and increase the contact area during back electrode preparation. The X-Ray diffraction, Raman spectroscopy, transmission electron microscopy, and scanning electron microscopy are used to characterize the crystallinity and crystal shape of pyramid-shaped CZTS monocrystal. Besides, Finite-Difference simulation calculation is employed to reveal the optical response and corresponding monograin layer solar cells performance of densely packed CZTS. The results show that the pyramid-shaped structure exhibited excellent incident light trapping ability, and the simulated device achieves a cell efficiency with above 13.6% after parameter optimization. The work provides a method for preparing pyramid-shaped CZTS monocrystal, and a new strategy to further improve the efficiency of CZTS-based monograin layer solar cells.