Unraveling radiation damage and healing mechanisms in halide perovskites using energy-tuned dual irradiation dosing.

Perovskite photovoltaics have been shown to recover, or heal, after radiation damage. Here, we deconvolve the effects of radiation based on different energy loss mechanisms from incident protons which induce defects or can promote efficiency recovery. We design a dual dose experiment first exposing devices to low-energy protons efficient in creating atomic displacements. Devices are then irradiated with high-energy protons that interact differently. Correlated with modeling, high-energy protons (with increased ionizing energy loss component) effectively anneal the initial radiation damage, and recover the device efficiency, thus directly detailing the different interactions of irradiation. We relate these differences to the energy loss (ionization or non-ionization) using simulation. Dual dose experiments provide insight into understanding the radiation response of perovskite solar cells and highlight that radiation-matter interactions in soft lattice materials are distinct from conventional semiconductors. These results present electronic ionization as a unique handle to remedying defects and trap states in perovskites.

Role of the electronically-active amorphous state in low-temperature processed In2O3 thin-film transistors.

Metal oxide (MO) thin-film transistors (TFTs) are expected to enable low-cost flexible and printed electronics, given their excellent charge transport, low processing temperatures and solution processability. However, achieving adequate mobility when processed scalably at low temperatures compatible with plastic electronics is a challenge. Here, we explore process-structure-transport relationships in blade-coated indium oxide (In2O3) TFTs via both sol-gel and combustion chemistries. We find that the sol-gel chemistry enables n-type TFTs when annealed at 200 °C to 225 °C with noticeable electron mobility ((3.4 ± 1.3) cm2V-1s-1) yet minimal In2O3 crystallinity and surprisingly low levels of the metal-oxygen-metal (M-O-M) lattice content (≈46 %). Increased annealing temperatures result in the appearance of nanocrystalline domains and an increase in M-O-M content to ≈70 %, without any further increase in mobility. An actetylacetone combustion-assisted ink lowers the external thermal budget required for In2O3 crystallization but bypasses the electronically-active amorphous state and underperforms the sol-gel ink at low temperatures. Grain boundary formation and nanocrystalline inclusions in these films due to rapid combustion-assisted crystallization are suggested to be the likely origin behind the significantly compromised charge transport at low-temperatures. Overall, this study emphasizes the need to understand the complex interplay between local order (nanocrystallinity) and connectivity (grain boundary, amorphous phases) when optimizing low-temperature processed MO thin films.