Thermal stability enhancement of perovskite MAPbI(3) film at high temperature (150 degrees C) by PMMA encapsulation

• Main Authors: Soo, Yew Hang, Ng, Soo Ai, Wong, Yew Hoong, Ng, Chai Yan
• Format: Article
• Published: Springer 2021
• Subjects: QC Physics; TA Engineering (General). Civil engineering (General)
• Online Access: http://eprints.um.edu.my/26730/
• Institution: Universiti Malaya

Methylammonium lead iodide (MAPbI(3)) is a perovskite material functioning as a light-absorbing layer in a perovskite solar cell (PSC). However, many works reported the poor thermal stability of MAPbI(3), which hindered the direct annealing of low-temperature processed (<= 150 degrees C) metal oxide sols as a charge transport layer (CTL) on top of it. In this work, a poly(methyl methacrylate) (PMMA) layer was spin coated onto the ambient air-prepared MAPbI(3) film to act as an encapsulation layer. The encapsulated MAPbI(3) film was annealed at 150 degrees C for 1-5 h. The PMMA passivated the grain boundary defects located at film/air interface and extended the onset of thermal degradation time up to 3 h, which is significantly longer than the annealing time required for metal oxide sol CTLs. The MAPbI(3) phase also remained dominant even after 5 h of annealing, showing its high thermal stability. With this thermal stability enhancement, it would open a pathway for the fabrication of PSCs with metal oxide sol CTLs that are low cost, high stability, as well as low temperature processed (<= 150 degrees C).