Very high values of carrier mobility have been recently reported in newly developed materials for field-effect transistors (FETs) or thin-film transistors (TFTs). However, there is an increasing concern of whether the values are overestimated. In this paper, we investigate how much contact resistance a FET or TFT can tolerate to allow the conventional current-voltage equations, which is derived for no contact resistance. We contend that mobility in transistors with resistive contact can be underestimated with the presence of the injection barrier, whereas mobility in transistors with gated Schottky contact can be overestimated by more than 10 times. The latter phenomenon occurs even in long-channel devices, and it becomes more severe when using low-$k$ dielectrics. This is because the band bending and injection barrier experience a complicated evolution on account of electrostatic doping in the semiconducting layer; thus, they do not follow a capacitance approximation. When the band bending is weak, the accumulation is as weak as that in the subthreshold regime. Accordingly, the carrier concentration nonlinearly increases with the gate field. This mechanism can occur with or without exhibiting the “kink” feature in the transfer curves, which has been suggested as the signature of overestimation. For precision, carrier mobility should be presented against gate voltage and should be examined by other recommended extraction methods.

The generalized Einstein relation (GER) can unify various theoretical models and predict charge transport in OSCs with various crystallinities, by altering the variance of the density of states and the delocalization degree in a Gaussian-distributed density of states.

Semiconductor vacancy engineering has remained a prominent growing field over the past several decades. Modulating electronic structures and surface properties has sparked considerable interest in vacancy-modified photocatalysts. Given vacancy-mediated photocatalysis has only been developed for a relatively short period, significant advance has been made in enhancing light absorption over the full solar spectrum, the efficiency of charge transfer and separation and surface reaction kinetics. This review seeks to highlight the recent impressive progress in vacancy-enhanced photocatalysis. First, we summarize the crafting and characterization of vacancies after defining the classification of vacancies. Second, current developments of semiconductor vacancy engineering in several photocatalysts (i.e., metal oxides, hydroxides, sulfides, Sillén phase related bismuth-containing materials and g-C₃N₄) are emphasized, focusing on the mechanism of vacancies in regulating the photocatalytic performance. Finally, prospects and challenges regarding vacancy engineering of photocatalytic materials are concluded.

Timely and remote biomarker detection is highly desired in personalized medicine and health protection but presents great challenges in the devices reported so far. Here, we present a cost-effective, flexible and self-powered sensing device for H₂S biomarker analysis in various application scenarios based on the structure of galvanic cells. The sensing mechanism is attributed to the change in electrode potential resulting from the chemical adsorption of gas molecules on the electrode surfaces. Intrinsically stretchable organohydrogels are used as solid-state electrolytes to enable stable and long-term operation of devices under stretching deformation or in various environments. The resulting open-circuit sensing device exhibits high sensitivity, low detection limit, and excellent selectivity for H₂S. Its application in the non-invasive halitosis diagnosis and identification of meat spoilage is demonstrated, emerging great commercial value in portable medical electronics and food security. A wireless sensory system has also been developed for remote H₂S monitoring with the participation of Bluetooth and cloud technologies. This work breaks through the shortcomings in the traditional chemiresistive sensors, offering a direction and theoretical foundation for designing wearable sensors catering to other stimulus detection requirements.