Modulating Cationic Ratios for High-Performance Transparent Solution-Processed Electronics

Amorphous oxide semiconductors such as indium zinc tin oxide (IZTO) are considered favorites to serve as channel materials for thin film transistors (TFTs) because they combine high charge carrier mobility with high optical transmittance, allowing for the development of transparent electronics. Although the influence of relative cationic concentrations in determining the electronic properties have been studied in sputtered and PLD films, the development of printed transparent electronics hinges on such dependencies being explored for solution-processed systems. Here, we study solution-processed indium zinc tin oxide thin film transistors (TFTs) to investigate variation in their electrical properties with change in cationic composition. Charge transport mobility ranging from 0.3 to 20.3 cm²/(V s), subthreshold swing ranging from 1.2 to 8.4 V/dec, threshold voltage ranging from −50 to 5 V, and drain current on–off ratio ranging from 3 to 6 orders of magnitude were obtained by examining different compositions of the semiconductor films. Mobility was found to increase with the incorporation of large cations such as In³⁺ and Sn⁴⁺ due to the vast s-orbital overlap they can achieve when compared to the intercationic distance. Subthreshold swing decreased with an increase in Zn²⁺ concentration due to reduced interfacial state formation between the semiconductor and dielectric. The optimized transistor obtained at a compositional ratio of In/Zn/Sn = 1:1:1, exhibited a high field-effect mobility of 8.62 cm²/(V s), subthreshold swing of 1.75 V/dec, and current on–off ratio of 10⁶. Such impressive performances reaffirm the promise of amorphous metal oxide semiconductors for printed electronics

Transparent Flexible Multifunctional Nanostructured Architectures for Non-optical Readout, Proximity, and Pressure Sensing

Electronic skins need to be versatile and able to detect multiple inputs beyond simple pressure and touch while having attributes of transparency and facile manufacturability. Herein, we demonstrate a versatile nanostructured transparent sensor capable of detecting wide range of pressures and proximity as well as novel nonoptical detection of printed patterns. The architecture and fabrication processes are straightforward and show robustness to repeated cycling and testing. The sensor displays good sensitivity and stability from 30 Pa to 5 kPa without the use of microstructuration and is conformal and sensitive to be utilized as a wrist-based heart-rate monitor. Highly sensitive proximity detection is shown from a distance of 9 cm. Finally, a unique nonoptical pattern recognition dependent on the difference in the dielectric constant between ink and paper is also demonstrated, indicating the multifunctionality of this simple architecture

Strongly Confined CsPbBr₃ Quantum Dots as Quantum Emitters and Building Blocks for Rhombic Superlattices

The success of the colloidal semiconductor quantum dots (QDs) field is rooted in the precise synthetic control of QD size, shape, and composition, enabling electronically well-defined functional nanomaterials that foster fundamental science and motivate diverse fields of applications. While the exploitation of the strong confinement regime has been driving commercial and scientific interest in InP or CdSe QDs, such a regime has still not been thoroughly explored and exploited for lead-halide perovskite QDs, mainly due to a so far insufficient chemical stability and size monodispersity of perovskite QDs smaller than about 7 nm. Here, we demonstrate chemically stable strongly confined 5 nm CsPbBr3 colloidal QDs via a postsynthetic treatment employing didodecyldimethylammonium bromide ligands. The achieved high size monodispersity (7.5% ± 2.0%) and shape-uniformity enables the self-assembly of QD superlattices with exceptional long-range order, uniform thickness, an unusual rhombic packing with an obtuse angle of 104°, and narrow-band cyan emission. The enhanced chemical stability indicates the promise of strongly confined perovskite QDs for solution-processed single-photon sources, with single QDs showcasing a high single-photon purity of 73% and minimal blinking (78% “on” fraction), both at room temperature