研究目的
Investigating the effect of hexagonal boron nitride (h-BN) as a surface passivation layer on the photovoltaic performance of two-dimensional (2D) van der Waals (vdW) heterojunction solar cells, specifically MoS2/WSe2 solar cells, to reduce electrical loss and improve efficiency and stability.
研究成果
The application of an h-BN passivation layer significantly improves the photovoltaic performance and stability of MoS2/WSe2 heterojunction solar cells by reducing the recombination rate at the junction and surface of non-overlapped semiconductor regions. This simple and effective passivation method offers a promising approach to enhancing the efficiency and durability of 2D vdW heterojunction solar cells.
研究不足
The study is limited by the small active area of the devices due to the use of mechanically exfoliated 2D flakes, which may not represent the performance of larger, wafer-scale devices. Additionally, the long-term stability was only evaluated over a month, and further studies are needed to assess the durability over longer periods.
1：Experimental Design and Method Selection:
The study involved the fabrication of MoS2/WSe2 heterojunction solar cells with and without an h-BN passivation layer to evaluate its impact on photovoltaic performance and stability. The photovoltaic properties were measured under AM 1.5G illumination. Time-resolved photoluminescence (TRPL) analysis was conducted to understand the mechanism of performance enhancement.
2：5G illumination. Time-resolved photoluminescence (TRPL) analysis was conducted to understand the mechanism of performance enhancement.
Sample Selection and Data Sources:
2. Sample Selection and Data Sources: MoS2 and WSe2 multilayers were prepared by mechanical exfoliation of bulk crystals. The thickness of the flakes was determined by optical contrast, and heterostructures were fabricated using a PDMS-mediated deterministic transfer process.
3：List of Experimental Equipment and Materials:
Equipment included an atomic force microscope (AFM) for characterization, a transmission electron microscope (TEM) for cross-sectional analysis, a Keithley 4200 parameter analyzer for electrical measurements, and a solar simulator system for photovoltaic performance evaluation. Materials included MoS2, WSe2, and h-BN multilayers.
4：Experimental Procedures and Operational Workflow:
The fabrication process involved transferring MoS2 and WSe2 flakes onto a glass substrate, forming a heterojunction, and then transferring an h-BN layer on top. Photovoltaic properties were measured before and after h-BN passivation. TRPL measurements were conducted to analyze carrier lifetime.
5：Data Analysis Methods:
The photovoltaic performance was evaluated based on short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE). TRPL decay spectra were analyzed using exponential fitting to calculate average recombination lifetime.
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