Re-texturization of monocrystalline silicon wafers for second-life solar cells: A waste-to-wealth approach

The world is progressively moving towards greener energy sources to meet the goal of net carbon neutrality by 2050, and an accelerated rate of deployment of photovoltaic modules is witnessed internationally. At the end of their life, photovoltaic modules must be recycled to promote sustainable development goals and to restrict the escalation of dangerous pollutants from spent modules. The silicon wafer can be recovered through destructive or non-destructive routes. If the monocrystalline Si wafers are retrieved via the non-destructive method, they can serve as a substrate for second-life solar cells after re- texturization. An imminent challenge of wafer re-texturization requires attention to fabricate second-life solar cells. Due to the surface conditions of a junction-removed wafer, it is often challenging to texture the recovered wafer with a surface reflectance similar to that of a virgin wafer. The height of the pyramidal structure, generated due to the directional etching of silicon via potassium hydroxide solution, must be controlled to integrate such refurbished wafers into the traditional solar cell fabrication process. This work produces a Si wafer with resistivity~l ohm-cm, thickness~127-130 μm, and reflectivity~13- 14%. Repurposing the recovered silicon wafer could add tremendous economic value to the global economy, avoid the energy cost during manufacturing, starting from ingot production to solar-grade silicon wafer fabrication, and effectively reduce the energy-payback time of the photovoltaic sector, promoting resource efficiency.