LOCAL-HEAT · Controlled Local Heating to Crystallize Solution-based Semiconductors for Next-Generation Solar Cells and Optoelectronics

Solution-processed semiconductor thin-films have recently emerged as promising candidates for optoelectronic devices such as light-emitting diodes (LEDs), sensors and solar cells. One example is hybrid perovskite films that are processed inexpensively by crystallization from a solution and have the disruptive potential for efficient energy production and consumption. However, current crystallization methods from solution often result in uncontrolled film growth with ragged, degradation-prone grain boundaries. The lack of quality materials with large, controlled grains holds back solution-based semiconductors.The core hypothesis of LOCAL-HEAT is that controlling the fundamental crystallization kinetics of semiconductor films, when transitioning from the liquid precursor to the final solid-state, governs ultimate performance and long-term stability. This is key to creating materials that are: a) sustainable, b) stable and c) show highest performance.To achieve this challenging goal, I will control the crystallization kinetics of liquid multicomponent semiconductor inks by turning light into localized heat packages to cause confined supersaturation. This will induce seeds to crystallize the liquid precursor into high-quality films.Local heat will be realized by developing two methods: a) laser annealing by a tunable light pattern, projected on a liquid precursor film, and b) thermoplasmonic heating of plasmonic nanoparticles acting as antennas to turn incoming light into a localized heat nanobubble within a liquid ink.Achieving sustainable materials with highest quality crystallization will enable perovskite solar cells with performances >26% and stabilities of >30 years. Consequently, it will also revolutionize solution-processed semiconductors in general. LOCAL-HEAT will thus enable key technological applications in optoelectronics, e.g., solar cells, LEDs and scintillation detectors, and beyond.