Thickness Effects on the Thermal Expansion Coefficient of Indium Tin Oxide/Polyethylene Terephthalate Film

Lead-Free Flexible Perovskite Solar Cells with Interfacial Native Oxide Have >10% Efficiency and Simultaneously Enhanced Stability and Reliability

“…where the CTE α MHP value for FASnI 3 is ∼37 × 10 −6 °C−1 46 and that for the substrate α ITO/PET is ∼12 × 10 −6 °C−1 47 FASnI 3 value is used here.) Thus, σ R is estimated to be a modest ∼24 MPa, which augments the applied uniaxial tensile stress, σ A .…”

“…Since h ≈ 185 μm, the σ A value is estimated to be ∼150 MPa. Additionally, the as-processed MHP thin film is typically under equibiaxial residual tension (σ R ) due to the coefficient of thermal expansion (CTE) mismatch with the substrate, which is given by where the CTE α MHP value for FASnI 3 is ∼37 × 10 –6 °C –1 and that for the substrate α ITO/PET is ∼12 × 10 –6 °C –1 and the temperature range through which the MHP thin film is cooled is Δ T = 77 °C (100–23 °C). (The CTE of FASn 0.9 Ge 0.1 I 3 MHP has not been measured; therefore, the FASnI 3 value is used here.)…”