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The hydrovoltaic effect is a recently‐developed means to directly generate electric power from omnipresent water resources, which has drawn substantial attention in the energy harvesting and conversion domain. Unfortunately, the output power density significantly lags behind the other power generation ways. Although numerous efforts have been made to develop various active materials catering to improved output, yet less attention has been paid to the interface between active materials and electrodes. Here, an atomic layer deposition deposited titanium oxide layer is incorporated at rear silicon contact, enabling high surface passivation quality and superior electron selectivity characteristics. As a consequence, the passivated rear contact remarkably enables elevated hydrovoltaic performance, yielding a high open‐circuit voltage of ≈0.82 V and a short‐current density of ≈30 µA cm−2 at room temperature, and the output power density of ≈15 µW cm−2 displays the highest value among previously reported comparable hydrovoltaic devices. This finding that regards the leverage of transition metal oxide as a passivation layer presents a prospective avenue to improve interfacial contact for high‐efficiency hydrovoltaic devices. [ABSTRACT FROM AUTHOR]

Inkjet printing is a powerful technology for realizing high‐density pixelated perovskite light‐emitting diodes (PeLEDs). However, the coffee‐stain effect in the inkjet printing process often leads to uneven thickness and poor crystallization of printed perovskite features, which deteriorates the performance of PeLEDs. Here, a strategy is developed to suppress the coffee‐stain effect via enhancing Marangoni flow strength. An interfacial poly(vinylpyrrolidone) (PVP) layer is incorporated to tune the surface tension of the underlying hole transport layer (HTL) and enhance the perovskite crystallization. The substrate temperature is also carefully controlled to tune the printing solvent evaporation rate rationally. By optimizing the thickness of the PVP layer and the temperature of the printing stage, the coffee‐stain effect is dramatically restrained. In addition, the interfacial insulating PVP layers play a positive role in suppressing leakage current level of PeLEDs by avoiding any direct electrical contact between HTL and electron transporting layer. Finally, an inkjet‐printed PeLED with a brightness of 3640 cd m–2 and external quantum efficiency of 9.0% is achieved. This work highlights the availability of inkjet‐printing technology for fabricating patterned PeLEDs in information display applications. [ABSTRACT FROM AUTHOR]