During the photovoltaic cell production process, multiple steps generate smoke, harmful gases, and odors.
1. Silicon Material Processing and Purification
Pollutants:
Dust: Micron-sized silicon powder produced by polysilicon crushing and screening.
Harmful Gases: Silicon tetrachloride (SiCl₄) and hydrogen chloride (HCl, a byproduct of the silane reduction reaction).
Odor: The pungent odor of chlorosilane volatilization.
2. Silicon Wafer Cutting (Wire Cutting/Diamond Wire Cutting)
Pollutants:
Dust: Silicon powder and metal debris produced by silicon carbide (SiC) or diamond wire cutting.
VOCs: Organic waste gases produced by the volatilization of cutting fluids (polyethylene glycol, oil-based solvents).
3. Texturing and Cleaning
Pollutants:
Acid/Alkaline Mist: Volatilization of hydrofluoric acid (HF), nitric acid (HNO₃), or sodium hydroxide (NaOH) during the texturing process.
Wastewater and Exhaust Gases: Residual VOCs from isopropyl alcohol (IPA) cleaning agents.
4. Diffusion (Phosphorus/Boron Doping)
Pollutions:
Highly Toxic Gases: Cl₂ and P₂O₅ particles produced by the decomposition of phosphine (PH₃) and phosphorus oxychloride (POCl₃).
Acidic Gases: HCl and Cl₂ in the exhaust gas from the diffusion furnace.
5. Plasma Etching (PECVD/PVD)
Pollutions:
Harmful Gases: Residual gases from incomplete reactions of silane (SiH₄) and ammonia (NH₃).
Particles: Nano-scale dust produced by silicon nitride (SiNₓ) coating.
6. Screen Printing and Sintering
Pollutions:
VOCs: Volatile organic solvents (terpineol, ethyl cellulose) in silver and aluminum pastes.
Metallic Fumes: Lead and silver oxide particles produced by the high temperatures of the sintering furnace.
7. Module Encapsulation (EVA Lamination)
Contaminants:
VOCs: Acetic acid and aldehyde gases released during hot pressing of ethylene vinyl acetate (EVA).
Odor: A pungent odor during film curing.
