Angle-Resolved Time-Resolved Microwave Conductivity

The contactless electronic characterization technique time resolved microwave conductivity (TRMC) provides a very convenient way of quickly evaluating carrier mobilities and lifetimes for a variety of semiconducting materials. However, the technique has one notable limitation in that it can conventionally only be used to resolve carrier mobilities in the plane of substrate (lateral mobility).

Here we present a novel approach for resolving charge carrier mobilities in different planes within a sample. Using a range of 3D-printed samples holders, where the sample is held at various angles relative to the incident light, we are able to resolve the mobility in the plane of the sample and out of the plane of the sample. Because charges generally travel in the direction perpendicular to the substrate in solar cells, identifying carrier mobility in this direction is particularly valuable. We studied the archetypical hybrid halide perovskite compound, methylammonium lead iodide. Our results show that for films prepared using our solution-processing route, mobilities in-plane are significantly higher than those out-of-plane.