Semiconducting transparent metal oxides are critical high mobility materials for flexible optoelectronic devices such as displays. We introduce the continuous liquid metal printing (CLMP) technique to enable rapid roll-to-roll compatible deposition of semiconducting two-dimensional (2D) metal oxide heterostructures. We leverage CLMP to deposit 10 cm2-scale nanosheets of InO x and GaO x in seconds at a low process temperature (T < 200 °C) in air, fabricating heterojunction thin film transistors with 100× greater I on/I off, 4× steeper subthreshold slope, and a 50% increase in mobility over pure InO x channels. Detailed nanoscale characterization of the heterointerface by X-ray photoelectron spectroscopy, UV–vis, and Kelvin probe elucidates the origins of enhanced electronic transport in these 2D heterojunctions. This combination of CLMP with the electrostatic control induced by the heterostructure architecture leads to high performance (μlin up to 22.6 cm2/(V s)) while reducing the process time for metal oxide transistors by greater than 100× compared with sol–gels and vacuum deposition methods.

The photocurrent generation in dilute donor organic solar cells (DDOSCs) based on fullerene and non-fullerene acceptors is compared. The donor concentration is kept under 5 wt % to avoid the formation of a percolation pathway for hole transport, as verified by studying the hole mobilities in an insulating polymer matrix. The short-circuit current densities (J sc ) in DDOSCs for three common acceptors are quantified in terms of charge generation, transport, and collection, which are probed using ideal J sc calculated from the transfer matrix method, hole mobility measured from space charge limited current method, and charge collection efficiency, respectively. Using non-fullerene acceptors improves both charge generation and transport, with charge transport being more important in determining J sc in DDOSCs.

Defects and impurities in halide perovskite solar cells can negatively impact device performance and long-term stability. In this study, we identify photonically cured methylammonium (MA) lead iodide films containing a residual adduct, MA2Pb3I8(dimethyl sulfoxide)2 (MA2Pb3I8(DMSO)2), which reduces photocurrent generation in perovskite solar cells (PSCs). This is evidenced by a decrease in the external quantum efficiency (EQE) near 400 nm. Similar EQE reductions were observed in PSCs produced using high-speed processes but have not been thoroughly examined. Through X-ray diffraction patterns and Fourier transform infrared spectroscopy, we establish the photoinactive MA2Pb3I8(DMSO)2 as the culprit for the EQE reduction. Combined experimental and simulation results reveal that the MA2Pb3I8(DMSO)2 phase is located at the hole transport layer/interface, not on the surface, resulting in lower quantum efficiency and surface photovoltage in the short-wavelength region. The residual adduct is kinetically trapped due to the short processing time (20 ms) and crystallization direction but can be removed by an additional photonic pulse. This study highlights the need for careful examination of resulting materials beyond device efficiency when transitioning from laboratory processing to industrial high-speed methods.

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