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The photovoltaic devices offer promising eco‐friendly solution for self‐powered flexible electronics. However, their fabrication on flexible substrate is not easy due to mismatches between the requirements of conventional microfabrication and the thermal, and mechanical features of the substrates. Herein, direct roll printed nanoscale photoactive electronic layers are presented, which are further processed to develop ≈315 µm2 sized miniaturized photovoltaic microcells. Using a set of 32 microcells, connected in parallel configuration, indoor light harvesting is shown at a maximum power density of ≈10 µW cm−2 under white LED illumination. Further, the dual functionality of developed microcells i.e., energy harvesting as well as wideband photodetection is demonstrated. As self‐powered photo sensors the developed photovoltaic microcells exhibit distinctive photo responses under white LED‐UV (365 nm)‐ NIR (850 nm) light illumination, with exceptionally high‐speed response (rise time τRise = 205 µs and fall time τFall = 2000 µs), and a peak responsivity of 2.48 A W−1 to UV light at zero bias voltage. The presented results show the potential usage of printed multifunctional photovoltaic microcells in a wide variety of applications such as self‐powered wearable and flexible electronic systems for health monitoring and indoor robotics. [ABSTRACT FROM AUTHOR]

Flexible hybrid electronics (FHE) is an emerging area that combines printed electronics and ultra‐thin chip (UTC) technology to deliver high performance needed in applications such as wearables, robotics, and internet‐of‐things etc. The integration of UTCs on flexible substrates and the access to devices on them requires high resolution interconnects, which is a challenging task as thermal and mechanical mismatches do not allow conventional bonding methods to work. To address this challenge, the resource‐efficient, area‐efficient, and low‐cost printing routes for obtaining vertical interconnection accesses (VIAs) are demonstrated here. It is demonstrated how high‐resolution printers (electrohydrodynamic and extrusion‐based direct‐ink writing printers) can be used for patterning of high‐resolution, freeform, vertical conductive structures. To access the transistors on UTCs, the VIAs, obtained using conventional photolithography and plasma etching steps, are filled with conductive silver nanoparticle‐based ink/paste using high‐resolution printers. Comprehensive studies are performed to compare and benchmark in terms of: i) the printing speed and throughput of the printers, ii) the electrical performance of vertically connected transistors in UTCs, and iii) the electrical performance stability of FHE system (interconnects and UTCs) under mechanical bending conditions. This in‐depth study shows the potential use of printing technologies for development of high‐density 3D integrated FHE systems. [ABSTRACT FROM AUTHOR]

Flexible hybrid electronics (FHE) offers potential for fast computation and communication needed in applications such as human–machine interfaces, electronic skin, etc. FHE typically comprises devices that can vary from nano‐ to chip scale, and their integration using a common process is often challenging. Herein, a printed electronics route is presented to integrate the ultrathin chips (chip‐scale) and nanowires (NWs)‐based electronic layers (nanoscale) on the same substrate. The fabrication process is categorized into three stages: i) direct transfer printing of ultrathin chips (UTCs), ii) contact printing of nanoscale structures, and iii) metal printing using the direct ink write (DIW) method to define electrodes/interconnects. The UTC printing process is carefully optimized by studying the performance of transistors present on them. Electrical data collected from 14 transistors located on 3 different chips show negligible variation in performance after they are transfer printed—thus confirming the efficacy of the printing technique. The superior grade quality of ZnO‐NWs‐based electronic layers printed on the same substrate is also demonstrated by constructing UV photodetectors using DIW printing. The photodetectors show high responsivity (≈2 × 107 A W−1) and specific detectivity (≈5 × 1015 Jones) at a low UV intensity of 0.5 µW cm−2. [ABSTRACT FROM AUTHOR]

Nano/microstructures of compound semiconductors such as gallium arsenide (GaAs) demonstrate enormous potential for advanced photonic technologies as they provide realistic means for miniaturization of optoelectronic devices that feature better performance and low power consumption. However, intimately integrating them onto flexible substrates is challenging and restricts their use in the next generation of applications such as wearables and soft robotics. Herein, printed arrays of well‐defined and laterally aligned semi‐insulating (undoped) and doped GaAs microstructures are presented to develop high‐performance flexible broadband photodetectors. The direct roll transfer printed GaAs microstructures‐based photodetectors exhibit excellent performance under ultraviolet and near‐infrared illumination, including ultrafast response (2.5 ms) and recovery (8 ms) times, high responsivity (>104 AW–1), detectivity (>1014 Jones), external quantum efficiency (>106), and photoconductive gain (>104) at low operating voltage of 1 V. The achieved performance is among the best reported for broadband photodetectors but with an added benefit of the developed devices having a flexible form factor. Further, the photodetectors show stable performance under mechanical bending (500 cycles) and twisting loading. The developed materials and manufacturing route can enable high‐speed communications and computation via high‐performance flexible electronics and optoelectronics and transform numerous emerging applications such as wearable systems and internet of things. [ABSTRACT FROM AUTHOR]

High‐performance flexible electronics developed with resource efficient printing route will transform the way future electronics is manufactured and used to advance applications such as healthcare, Internet of Things, wearables, consumer electronics, etc. Herein, an innovative approach is presented that involves, for the first time, the in‐tandem use of contact and transfer printing methods to realize high‐quality electronic layers at selected locations on rigid (Si/SiO2), flexible (polyimide), and biodegradable (magnesium (Mg) foils). Superior grade quality of printed electronic layers is demonstrated by realizing transistors and printed UV photodetectors (PDs) employing high‐resolution electrohydrodynamic printing. The all‐printed PDs show extremely high performance for UV detection, with extraordinary high responsivity (>107 A W−1) and specific detectivity (≈1017 Jones) values at low UV intensity of 0.1 µW cm−2. Finally, the fabricated PDs on Mg foil are dissolved in deionized water at room temperature. Thus, in‐tandem contact and transfer printing has potential for ecofriendly development of transient electronics. Further, the approach allows printing of wide range of nanomaterials and heterostructures or complex superlattice structures, which can open exciting new possibilities for high‐performance electronics. [ABSTRACT FROM AUTHOR]