Thermal conductivity and diffusivity of triple-cation perovskite halide materials for solar cells

摘要

We report on the measurement of thermal conductivity and thermal diffusivity by a modulated thermoreflectance microscopy technique on a mixed-cation perovskite material [Cs_(0.05)(formamidinium_(0.83)methylammonium_(0.17))_(0.95)Pb(I_(0.83)Br_(0.17))_3] widely applied for solution-processed perovskite solar cells. Such materials are supposed to present improved thermal stability compared to methylammonium-based single cation perovskites. Our measurements are performed on perovskite/TiO_2/SnO_2:F/SiO_2 structures, with perovskite thicknesses ranging between 250 nm and 1000 nm. This configuration is the one of a real solar cell, with the same substrate and intermediate layers as of an operating device. We measured a thermal conductivity k_(per) of 0.26 ± 0.03 W m~(-1) K~(-1) and a thermal diffusivity D_(per) of 3.5 × 10~(-7) ± 0.5 m~2 s~(-1). The value for thermal conductivity is comparable to the one measured on single cation perovskites, which is generally in the 0.2-0.6 range. The value for thermal diffusivity has not been reported previously.