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Hybrid organic–inorganic perovskites enable the production of semiconductor devices at low cost from solution processing. Their remarkable structural versatility offers unique and diverse physical properties, leading to their incorporation in a wide variety of applications. One major limitation is the significant negative environmental impact associated with developing perovskite devices; common solvents used in perovskite film deposition are highly toxic, which represents a barrier to the transfer to an industrial setting of the perovskite technology. Here we report on the fabrication and characterisation of the first laser printed organic–inorganic perovskite films. The method is solvent-free, scalable and low-cost, allowing fast deposition over large areas and with minimal material waste. We show that the laser printed perovskite films are crystalline and exhibit electrical properties on par with single crystals, despite the fact that the microstructure consists of randomly oriented crystallites. The toner used during printing is designed for optimal film transfer and the vertical separation of its components results in a segregation of the perovskite film in the middle of the stack, therefore also encapsulating the perovskite layer, a process that yields a remarkable resilience to defect formation upon environmental exposure.

Field‐effect transistors (FETs) are key elements in modern electronics and hence are attracting immense scientific and commercial attention. The recent emergence of metal halide perovskite materials and their tremendous success in the field of photovoltaics have triggered the exploration of their application in other (opto)electronic devices, including FETs and phototransistors. In this review, the current status of the field is discussed, the challenges are highlighted, and an outlook for the future perspectives of perovskite FETs is provided. First, attention is drawn to the device physics and the fundamental processes that influence these devices, including the role of ion migration and defects, effects of temperature, light, and measurement conditions. Next, the performance of perovskite transistors and phototransistors reported to date are surveyed and critically assessed. Finally, the key challenges that impede perovskite transistor progress are outlined and discussed. The insights gained from the study of other perovskite optoelectronic devices may be adopted to address these challenges and advance this exciting field of research closer to the industrial application are examined.

Hybrid organic–inorganic perovskites have recently gained immense attention due to their unique optical and electronic properties and low production cost, which make them promising candidates for a wide range of optoelectronic devices. But unlike most other technologies, the breakthroughs witnessed in hybrid perovskite optoelectronics have outgrown the basic understanding of the fundamental material properties. For example, the effectiveness of charge transport in relation to film microstructure and processing has remained elusive. In this study, field‐effect transistors are fabricated and evaluated in order to probe the nature and dynamics of charge transport in thin films of methylammonium lead iodide. A dramatic improvement is shown in the electrical properties upon solvent vapor annealing. The resulting devices exhibit ambipolar transport, with room‐temperature hole and electron mobilities exceeding 10 cm²V⁻¹s⁻¹. The remarkable enhancement in charge carrier mobility is attributed to the increase in the grain size and passivation of grain boundaries via the formation of solvent complexes.