Transparent low moisture permeable coating for perovskite solar cell encapsulation

The perovskite solar cell has potential to become next generation photovoltaics due to its high power conversion efficiency and easy processing. However, the perovskite solar cell is very sensitive to moisture and temperature which needs to be protected by low temperature processable moisture permeation coating. Furthermore, the encapsulating coating has to be transparent so the perovskite solar cell can be kept its transparency and used in integrated building structure or tandem with Si solar cell, etc. The coating material should be solventless which will not damage the perovskite layer and release any harmful volatile organic compounds during the coating application process. A solventless hybrid coating made from polyfluoroesterimide and silica nanoparticle has been developed which can be cured within minutes using mercury lamp (light intensity 935 W/m2) at room temperature. The coating exhibits low moisture permeation and high transparency. The performance improvement is due to the presence of water repelling characteristic of fluoro moiety and less moisture permeable inorganic silica component. The encapsulated devices exhibit long-term stability when they were subjected to the environment of 65 °C and 65%RH for >400 h.