High-Performance Vertical Organic Phototransistors Enhanced by Ferroelectrics

Abstract

Organic phototransistors with high sensitivity and responsivity to light irradiance have great potential applications in national defense, meteorology, industrial manufacturing, and medical security. However, undesired dark current and photoresponsivity limit their practical applications. Here, a novel vertical organic phototransistor combined with ferroelectric materials is developed. The device structure has nanometer channel length, which can effectively separate photogenerated carriers and reduce the probability of carrier recombination and defect scattering, thus improving the device performance of phototransistors. Moreover, by inserting the poly­(vinylidene fluoride-co-trifluoroethylene) (P­(VDF-TrFE)) ferroelectric layer, the Schottky barrier at the interface between the semiconductor and source can be adjusted by the polarization of the external electric field, which can effectively reduce the dark current of the phototransistor to further improve the device performance. Therefore, our phototransistors exhibit a high photoresponsivity of more than 5.7 × 105A/W, an outstanding detectivity of 1.15 × 1018 Jones, and an excellent photosensitivity of 5 × 107 under 760 nm light illumination, which are better than those of conventional lateral organic phototransistors. This work provides a new approach for the development of high-performance phototransistors, which opens a new pathway for organic phototransistors in practical application.

Spatial Adjustment Strategy to Improve the Sensitivity of Ionogels for Flexible Sensors

“…Without any change in chemical composition and ratio of the ionogel compared to B‐IG, the prepared sensor by B‐IG‐5 has the best sensitivity, whose GF is calculated as 1.9 at the strain of 100% (up to 1.6 times of B‐IG), and it increased to 2.82 at the strain of 300%. Figure 4c shows the GF versus strain for stretchable ionogel sensors based on various polymer and IL, [ 36–49 ] the type of polymer and IL basically determine the level of sensitivity. The detailed information and properties of our ionogel in different strains are listed in Table S4 (Supporting Information).…”

“…The GF of spatial adjusted ionogel (B‐IG‐5) is higher than all listed ionogels at the same strain in the strain range from 50% to 300%, except the ones in Ref. [ 3,44 ] , which did not form the chemical cross‐linking [ 3 ] or employed the totally different IL system 1‐ethyl‐3‐methylimidazolium dicyanamide. [ 44 ] This comparison could prove that the spatial adjustment strategy possesses high potential in improving the sensitivity of ionogel sensor.…”

“…[ 3,44 ] , which did not form the chemical cross‐linking [ 3 ] or employed the totally different IL system 1‐ethyl‐3‐methylimidazolium dicyanamide. [ 44 ] This comparison could prove that the spatial adjustment strategy possesses high potential in improving the sensitivity of ionogel sensor. Moreover, this spatial adjustment strategy is further verified in the ionogel reported in Ref.…”

An Optically, Electrically, Magnetically Controllable Dual‐Gate Phototransistor

“…[ 14–19 ] By endowing electronic devices with magnetic sensing capability, flexible electronics can be upgraded to behave touchless and hence, diversifying their applications in a variety of wearable smart systems, including human‐machine interactivity, medical care, soft robot, and etc. [ 20–23 ]…”

“…[14][15][16][17][18][19] By endowing electronic devices with magnetic sensing capability, flexible electronics can be upgraded to behave touchless and hence, diversifying their applications in a variety of wearable smart systems, including human-machine interactivity, medical care, soft robot, and etc. [20][21][22][23] An organic phototransistor, an essential role in optoelectronics, can be made flexibly with touchless output current modulation by light [24,25] and is promising for information technology. Recently, it has also been realized that its output current can be tuned by electric field [24][25][26] and magnetic field.…”