Tactile and temperature sensors are the key components for e-skin fabrication. Organic transistors, a kind of intrinsic logic devices with diverse internal configurations, offer a wide range of options for sensor design and have played a vital role in the fabrication of e-skin-oriented tactile and temperature sensors. This research field has attained tremendous advancements, both in terms of materials design and device architecture, thereby leading to excellent performance of resulting tactile/temperature sensors. Herein, a systematic review of organic transistor-based tactile and temperature sensors is presented to summarize the latest progress in these devices. Particularly, we focus on spotlighting various device structures, underlying mechanisms and their performance. Lastly, an outlook for the future development of these devices is briefly discussed. We anticipate that this review will provide a quick overview of such a rapidly emerging research direction and attract more dedicated efforts for the development of next-generation sensing devices towards e-skin fabrication.

Organic phototransistors (OPTs), compared to traditional inorganic counterparts, have attracted a great deal of interest because of their inherent flexibility, light-weight, easy and low-cost fabrication, and are considered as potential candidates for next-generation wearable electronics. Currently, significant advances have been made in OPTs with the development of new organic semiconductors and optimization of device fabrication protocols. Among various types of OPTs, small molecule organic single crystal phototransistors (OSCPTs) standout because of their exciting features, such as long exciton diffusion length and high charge carrier mobility relative to organic thinfilm phototransistors. In this review, a brief introduction to device architectures, working mechanisms and figure of merits for OPTs is presented. We then overview recent approaches employed and achievements made for the development of OSCPTs. Finally, we spotlight potential future directions to tackle the existing challenges in this field and accelerate the advancement of OSCPTs towards practical applications.

As high-performance organic semiconductors, π-conjugated polymers have attracted much attention due to their charming advantages including low-cost, solution processability, mechanical flexibility, and tunable optoelectronic properties. During the past several decades, the great advances have been made in polymers-based OFETs with p-type, n-type or even ambipolar characterics. Through chemical modification and alignment optimization, lots of conjugated polymers exhibited superior mobilities, and some mobilities are even larger than 10 cm²·V⁻¹·s⁻¹ in OFETs, which makes them very promising for the applications in organic electronic devices. This review describes the recent progress of the high performance polymers used in OFETs from the aspects of molecular design and assembly strategy. Furthermore, the current challenges and outlook in the design and development of conjugated polymers are also mentioned.

With the development of device engineering and molecular design, organic field effect transistors (OFETs) with high mobility over 10 cm²·V⁻¹·s⁻¹ have been reported. However, the nonideal doubleslope effect has been frequently observed in some of these OFETs, which makes it difficult to extract the intrinsic mobility OFETs accurately, impeding the further application of them. In this review, the origin of the nonideal double-slope effect has been discussed thoroughly, with affecting factors such as contact resistance, charge trapping, disorder effects and coulombic interactions considered. According to these discussions and the understanding of the mechanism behind double-slope effect, several strategies have been proposed to realize ideal OFETs, such as doping, molecular engineering, charge trapping reduction, and contact engineering. After that, some novel devices based on the nonideal double-slope behaviors have been also introduced.

Rubrene, a superstar in organic semiconductors, has achieved unprecedented achievements in the application of electronic devices, and research based on its various photoelectric properties is still in progress. In this review, we introduced the preparation of rubrene crystal, summarized the applications in organic optoelectronic devices with the latest research achievements based on rubrene semiconductors. An outlook of future research directions and challenges of rubrene semiconductor for applications is also provided.