High‐Performance Single‐Crystalline Perovskite Thin‐Film Photodetector

The best performing modern optoelectronic devices rely on single‐crystalline thin‐film (SC‐TF) semiconductors grown epitaxially. The emerging halide perovskites, which can be synthesized via low‐cost solution‐based methods, have achieved substantial success in various optoelectronic devices including solar cells, lasers, light‐emitting diodes, and photodetectors. However, to date, the performance of these perovskite devices based on polycrystalline thin‐film active layers lags behind the epitaxially grown semiconductor devices. Here, a photodetector based on SC‐TF perovskite active layer is reported with a record performance of a 50 million gain, 70 GHz gain‐bandwidth product, and a 100‐photon level detection limit at 180 Hz modulation bandwidth, which as far as we know are the highest values among all the reported perovskite photodetectors. The superior performance of the device originates from replacing polycrystalline thin film by a thickness‐optimized SC‐TF with much higher mobility and longer recombination time. The results indicate that high‐performance perovskite devices based on SC‐TF may become competitive in modern optoelectronics.     

An Ultrastable and High‐Performance Flexible Fiber‐Shaped Ni–Zn Battery based on a Ni–NiO Heterostructured Nanosheet Cathode

Currently, the main bottleneck for the widespread application of Ni–Zn batteries is their poor cycling stability as a result of the irreversibility of the Ni‐based cathode and dendrite formation of the Zn anode during the charging–discharging processes. Herein, a highly rechargeable, flexible, fiber‐shaped Ni–Zn battery with impressive electrochemical performance is rationally demonstrated by employing Ni–NiO heterostructured nanosheets as the cathode. Benefiting from the improved conductivity and enhanced electroactivity of the Ni–NiO heterojunction nanosheet cathode, the as‐fabricated fiber‐shaped Ni–NiO//Zn battery displays high capacity and admirable rate capability. More importantly, this Ni–NiO//Zn battery shows unprecedented cyclic durability both in aqueous (96.6% capacity retention after 10 000 cycles) and polymer (almost no capacity attenuation after 10 000 cycles at 22.2 A g^?1) electrolytes. Moreover, a peak energy density of 6.6 µWh cm^?2, together with a remarkable power density of 20.2 mW cm^?2, is achieved by the flexible quasi‐solid‐state fiber‐shaped Ni–NiO//Zn battery, outperforming most reported fiber‐shaped energy‐storage devices. Such a novel concept of a fiber‐shaped Ni–Zn battery with impressive stability will greatly enrich the flexible energy‐storage technologies for future portable/wearable electronic applications.     

High‐Performance,Ultrathin, Ultraflexible Organic Thin‐Film Transistor Array Via Solution Process

Ultrathin organic thin‐film transistors (OTFTs) have received extensive attention due to their outstanding advantages, such as extreme flexibility, good conformability, ultralight weight, and compatibility with low‐cost and large‐area solution‐processed techniques. However, compared with the rigid substrates, it still remains a challenge to fabricate high‐performance ultrathin OTFTs. In this study, a high‐performance ultrathin 2,7‐dioctyl[1]benzothieno[3,2‐b][1]benzothiophene (C8‐BTBT) OTFT array is demonstrated via a simple spin‐coating method, with mobility as high as 11 cm² V⁻¹ s⁻¹ (average mobility: 7.22 cm² V⁻¹ s⁻¹), on/off current ratio of over 10⁶, switching current of >1 mA, and a good yield ratio as high as 100%. The ultrathin thickness at ≈380 nm and the ultralight weight at ≈0.89 g m⁻² enable the free‐standing OTFTs to imperceptibly adhere onto human skin, and even a damselfly wing without affecting its flying. More importantly, the OTFTs show good electrical characteristics and mechanical stability when conformed onto the curved surfaces and even folded in a book after 100 folding cycles. These results illustrate the broad application potential of this simply fabricated ultrathin OTFT in next‐generation electronics such as foldable displays and wearable devices.