A Robotics-Guided Approach to Tune the Emission of 2D Perovskites Through Organic Cation Alloying

Tuning the optoelectronic properties of halide perovskite materials through alloying cations and halides has emerged as a powerful method to tailor these materials for specific applications, such as photovoltaics and LEDs. In two-dimensional perovskites, the organic spacer cation is typically considered as not impacting the electronic properties of the material. We show, however, that mixing different organic spacer cations tunes the emission of two-dimensional perovskites by controlling octahedral tilting of the inorganic layers. Using a homebuilt, high-throughput robotic system, we blend different organic cations and investigate their optical properties. Along with X-ray scattering and nanoscale imaging, we show that certain cation pairs mix and others phase separate. Our goal is to develop the materials design principles that dictate whether organic cations mix or demix when incorporated in a two-dimension perovskite, enabling new ways to tune the optical properties of these materials.