No abstract

In recent years, exciting advances have been achieved in pursuing organic thin film transistors (OTFTs) with high mobility. Whereas, the economical infeasibility of Au source/drain (S/D) electrodes that are widely used in OTFTs hinders the further development of OTFTs in industry. In this study, the modified indium tin oxide (ITO) as S/D electrodes is adopted. The ITO is modified by HCl aqueous solutions, its surface work function is improved from 4.8 to 5.5 eV. By first‐principle calculations and experiments, the charge analysis shows that the Cl atom traps 0.475 electrons, which indicates that In–Cl dipoles are responsible for the increase of the surface work function, besides the HCl modification leads to In+‐Cl− bonds instead of In3+‐Cl− bonds on the ITO surface compared with the reported InCl3 modification. More encouragingly, In+‐Cl− surface is found to have higher Cl density, higher work function and higher conductivity. TIPS‐pentacene, with suitable HOMO level of 5.2 eV, is adopted as organic semiconductor, and the bar‐coating process is optimized to realize oriented films. OTFTs with maximum field‐effect mobility of 0.77 cm2 V−1 s−1 are achieved. The ITO electrodes modified by HCl can be promising in the industry.

The photodetector based on methylammonium lead iodide (MAPbI3) is a promising device for wide wavelength range (380–780 nm) sensitivity. However, its industrial application is limited by the relatively low response speed to the light signal, which has received little attention. Only a few reports show low-bandwidth characteristics (less than 1 MHz at 0.1 cm2). Here, when a cosolvent strategy to manipulate the thickness and the crystallinity of the MAPbI3 film is adopted, photodetectors with a −3 dB bandwidth of 4.7 MHz are achieved (at 0.16 cm2 photo detecting area). The performance is significantly better than most of the organic and hybrid photodetectors reported so far. Based on this photodetector and an organic light-emitting diode (OLED), an organic optocoupler system with 1 MHz response frequency is successfully set up. Our results suggest that thickness-manipulated cosolvent strategy is a promising method in high-speed MAPbI3-based photodetectors.

Organic−inorganic lead halide perovskite materials have received great attention in recent years. However, the poor stability of these materials severely limits the commercial application of perovskite devices. Here, we used thiophene-2ethylammonium iodide (TEAI) material as the organic spacer NH 4 SCN and NH 4 Cl as the dual additives to realize high-stability two-dimensional (2D)/three-dimensional (3D) perovskite thin films for perovskite photodetectors. Then, we investigated different effects of the dual additives on the orientation and crystallinity of the perovskite films. At room temperature, the optimized 2D/3D perovskite photodetectors exhibit good performance with high external quantum efficiency (EQE) (72%), large responsivity (0.36 A/W), high detectivity (2.46 × 10 12 Jones at the bias of 0 V), high response frequency (1.7 MHz), and improved stability (retains 90% photocurrent after 2000 h storage in RT and 10% RH conditions). Based on these devices, a dual-channel optical transport system and a light-intensity adder are achieved. The results of this study indicate that, with a simple process, the TEAI and dualadditives based 2D/3D perovskite photodetectors have promising applications in light-intensity adder and optical communication systems.

Comprehensive SummaryTwo‐dimensional (2D) transition metal dichalcogenides (TMDCs) showed great potentials in 2D nanoelectronic devices due to their abundant and unique properties. The performance stability of the 2D TMDCs devices turns into one of the keys for their practical applications but has been rarely explored. Here, we investigated stability of MoS2 devices in ambient condition and contributed the device performance degradation to the surface oxidation of the contact metals with low work function, which increased the contact barrier and hindered the electron injection. We developed a new approach to recover the performance of the aged devices through the selective doping of contacts with organolithium, which prolonged the lifetime of MoS2 devices. Our work not only provides important insights into the stability of 2D TMDCs devices, but also opens up a new avenue for optimizing the performance of 2D MoS2 devices.