Castor oil-based polyurethane for affordable solar cell encapsulation

In the current work, we have employed an easy, simple, and cost-effective encapsulation process to enhance the lifespan of solar cells when exposed to challenging outdoor conditions. A solar cell was encapsulated using the liquid phase of a polyurethane elastomer prepared from low-cost vegetable castor oil, employing the simple and easy one-shot process with 2,4-toluene diisocyanate (TDI), and without the use of chain extenders. Optical transmission measurements revealed that the transparency of the encapsulant in the visible region reached 92 % with increasing TDI concentration, while the transparency was blocked in the ultraviolet (UV) region. Through the present work, the performance parameters of the solar cell have been enhanced after encapsulation with polyurethane under different compositions and thicknesses. The polyurethane encapsulant did not retain the applied temperature in the range of 30–150 °C, but rather transferred the heat outside the solar cell. We can conclude that the low-cost and easily prepared polyurethane is suitable for solar cell encapsulation in various environments, such as high temperatures (up to 150 °C), low solar intensity (due to high transmission up to 92 %), and high levels of UV radiation (due to UV-blocking capability). Additionally, the current polyurethane encapsulant can be prepared and cast into solar cells with different compositions, ranging from a flexible form (useful for flexible solar cell applications) to a rigid one with a glass-like structure, allowing for the encapsulation of solar cells without the use of a front sheet of glass cover.