The ability to image pressure distribution over complex three-dimensional surfaces would significantly augment the potential applications of electronic skin. However, existing methods show poor spatial and temporal fidelity due to their limited pixel density, low sensitivity, or low conformability. Here, we report an ultraflexible and transparent electroluminescent skin that autonomously displays super-resolution images of pressure distribution in real time. The device comprises a transparent pressure-sensing film with a solution-processable cellulose/nanowire nanohybrid network featuring ultrahigh sensor sensitivity (>5000 kPa⁻¹) and a fast response time (1000 dpi) pressure imaging without the need for pixel structures. Our approach provides a new framework for visualizing accurate stimulus distribution with potential applications in skin prosthesis, robotics, and advanced human-machine interfaces.

Thin-film transistor (TFT)-driven full-color organic light-emitting diodes (OLEDs) with vertically stacked structures are developed herein using photolithography processes, which allow for high-resolution displays of over 2,000 pixels per inch. Vertical stacking of OLEDs by the photolithography process is technically challenging, as OLEDs are vulnerable to moisture, oxygen, solutions for photolithography processes, and temperatures over 100 °C. In this study, we develop a low-temperature processed Al₂O₃/SiN_x bilayered protection layer, which stably protects the OLEDs from photolithography process solutions, as well as from moisture and oxygen. As a result, transparent intermediate electrodes are patterned on top of the OLED elements without degrading the OLED, thereby enabling to fabricate the vertically stacked OLED. The aperture ratio of the full-color-driven OLED pixel is approximately twice as large as conventional sub-pixel structures, due to geometric advantage, despite the TFT integration. To the best of our knowledge, we first demonstrate the TFT-driven vertically stacked full-color OLED.

Surface-exchanged, partially pyridine-functionalized colloidal quantum dot-based light-emitting diodes (QD-LEDs) that exhibit a low turn-on voltage and high brightness are reported. Pyridine is stochastically exchanged to a greater extent at the interface between the QDs and the hole transport layer via ligand exchange. Pyridine improves the charge balance within the QDs by enhancing the hole injection and hence lowers the turn-on voltage of the QD-LEDs. This strategy is applied to red-, green-, and blue-emitting (three primary colors) QD-LEDs. Pyridine-functionalized QD-LEDs (QD/py-LEDs) show enhanced maximum luminance, lowered driving voltages, and improved current- and power-efficiencies as compared with the original surface ligand-functionalized QD-LEDs. All three types of QD/py-LEDs show narrow emission spectra (full width at half maximum <40 nm) and cover 159% of the National Television System Committee 1987 color gamut.