Completely foldable electronics based on homojunction polymer transistors and logics

An increase in the demand for completely foldable electronics has motivated efforts for the development of conducting polymer electrodes having extraordinary mechanical stability. However, weak physical adhesion at intrinsic heterojunctions has been a challenge in foldable electronics. This paper reports the completely foldable polymer thin-film transistors (PTFTs) and logic gate arrays. Homojunction-based PTFTs were fabricated by selectively doping p-type diketopyrrolopyrrole-based semiconducting polymer films with FeCl3 to form source/drain electrodes. The doping process caused a gradual work function change with depth, which promoted charge injection to semiconducting regions and provided a low contact resistance. In addition, the interfacial adhesion in the PTFTs was improved by interfacial cross-linking between adjacent component layers. The electrical performance of the resulting PTFTs was maintained without noticeable degradation even after extreme folding, suggesting that the proposed fabrication strategy can further be applied to various semiconducting polymers for the realization of foldable electronics.

Influences of Work Function Changes in NO2 and H2S Adsorption on Pd-Doped ZnGa2O4(111) Thin Films: First-Principles Studies

The work function variations of NO2 and H2S molecules on Pd-adsorbed ZnGa2O4(111) were calculated using first-principle calculations. For the bonding of a nitrogen atom from a single NO2 molecule to a Pd atom, the maximum work function change was +1.37 eV, and for the bonding of two NO2 molecules to a Pd atom, the maximum work function change was +2.37 eV. For H2S adsorption, the maximum work function change was reduced from −0.90 eV to −1.82 eV for bonding sulfur atoms from a single and two H2S molecules to a Pd atom, respectively. Thus, for both NO2 and H2S, the work function change increased with an increase in gas concentration, showing that Pd-decorated ZnGa2O4(111) is a suitable material in NO2/H2S gas detectors.

Adsorption of NO2 and H2S on ZnGa2O4(111) Thin Films: A First-Principles Density Functional Theory Study

We performed first-principles total-energy density functional calculations to study the reactions of NO2 and H2S molecules on Ga–Zn–O-terminated ZnGa2O4(111) surfaces. The adsorption reaction and work functions of eight NO2 and H2S adsorption models were examined. The bonding of the nitrogen atom from a single NO2 molecule to the Ga atom of the Ga–Zn–O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of +0.97 eV. The bond joining the sulfur atom from a single H2S molecule and the Ga atom of Ga–Zn–O-terminated ZnGa2O4(111) surfaces exhibited a maximum work function change of −1.66 eV. Both results concur with previously reported experimental observations for ZnGa2O4-based gas sensors.

Study on Work Function of Modified Indium Tin Oxide and Performance of Organic Electroluminescent Devices.

ABSTRACTThe work function of the indium tin oxide electrode (ITO) modified by a self-assembled monolayer (SAM), which is used as an electrode in organic electroluminescent (EL) devices, was investigated in this study. It is revealed that chemical modification of ITO with p-substituted with different terminal groups (NH2−, Cl−, and CF3−) benzoic acids as a SAMs material with carboxyl binding group is caused to increase the work function of the ITO electrode. Through a self-assembly process, the transmittance of the ITO with a SAM was not changed. The work function change of ITO with various SAM was measured by using cyclic voltammetry. Characteristics of EL devices were increased because the energy barrier was decreased in an interface between the ITO and an organic layer in the EL devices. The correlation of the work function change and the performance of the chemically modified EL devices was estimated.