Today’s consumer electronics, such as cell phones, tablets and other portable electronic devices, are typically made of non-renewable, non-biodegradable, and sometimes potentially toxic (for example, gallium arsenide) materials. These consumer electronics are frequently upgraded or discarded, leading to serious environmental contamination. Thus, electronic systems consisting of renewable and biodegradable materials and minimal amount of potentially toxic materials are desirable. Here we report high-performance flexible microwave and digital electronics that consume the smallest amount of potentially toxic materials on biobased, biodegradable and flexible cellulose nanofibril papers. Furthermore, we demonstrate gallium arsenide microwave devices, the consumer wireless workhorse, in a transferrable thin-film form. Successful fabrication of key electrical components on the flexible cellulose nanofibril paper with comparable performance to their rigid counterparts and clear demonstration of fungal biodegradation of the cellulose-nanofibril-based electronics suggest that it is feasible to fabricate high-performance flexible electronics using ecofriendly materials.

Free-standing single crystalline semiconductor membranes have gained intensive attention over the last few years due to their versatile usage in many applications. This material platform possesses a high level of material quality similar to their bulk counterparts because single crystallinity is maintained. Si, Ge, and III–V based membranes have been widely studied for flexible electronic and optoelectronic devices such as thin-film transistors and photodetectors. However, the current status of research and development on free-standing single crystalline wide band-gap membranes is at a relatively early stage compared to IV and III–V based membranes. This review highlights recent advances in free-standing wide band-gap membranes, including GaN, SiC, ZnO, β-Ga₂O₃, and diamond and their applications. Fabrication techniques of each membrane are presented with material characterization. Some prospects for new research opportunities and challenges are also discussed.

Digital image sensors in hemispherical geometries offer unique imaging advantages over their planar counterparts, such as wide field of view and low aberrations. Deforming miniature semiconductor-based sensors with high-spatial resolution into such format is challenging. Here we report a simple origami approach for fabricating single-crystalline silicon-based focal plane arrays and artificial compound eyes that have hemisphere-like structures. Convex isogonal polyhedral concepts allow certain combinations of polygons to fold into spherical formats. Using each polygon block as a sensor pixel, the silicon-based devices are shaped into maps of truncated icosahedron and fabricated on flexible sheets and further folded either into a concave or convex hemisphere. These two electronic eye prototypes represent simple and low-cost methods as well as flexible optimization parameters in terms of pixel density and design. Results demonstrated in this work combined with miniature size and simplicity of the design establish practical technology for integration with conventional electronic devices.

High-yield, high throughput method creates nanomembrane photodetectors with unique optoelectronic properties.

Deep ultraviolet (UV) light-emitting diodes (LEDs) at a wavelength of 226 nm based on AlGaN/AlN multiple quantum wells using p-type Si as both the hole supplier and the reflective layer are demonstrated. In addition to the description of the hole transport mechanism that allows hole injection from p-type Si into the wide bandgap device, the details of the LED structure which take advantage of the p-type Si layer as a reflective layer to enhance light extraction efficiency (LEE) are elaborated. Fabricated LEDs were characterized both electrically and optically. Owing to the efficient hole injection and enhanced LEE using the p-type Si nanomembranes (NMs), an optical output power of 225 μW was observed at 20 mA continuous current operation (equivalent current density of 15 A/cm²) without external thermal management. The corresponding external quantum efficiency is 0.2%, higher than any UV LEDs with emission wavelength below 230 nm in the continuous current drive mode. The study demonstrates that adopting p-type Si NMs as both the hole injector and the reflective mirror can enable high-performance UV LEDs with emission wavelengths, output power levels, and efficiencies that were previously inaccessible using conventional p-i-n structures.