We performed a systematic study of the influence of environmental conditions on the electrical performance characteristics of solution-processed 2,7-dioctyl [1] benzothieno[3,2-b][1]-benzothiophene (C8-BTBT) thin-film transistors (TFTs). Four environmental exposure conditions were considered: high vacuum (HV), O 2 , N 2 , and air. The devices exposed to O 2 and N 2 for 2 h performed in a manner similar to that of the device kept in HV. However, the device exposed to air for 2 h exhibited significantly better electrical properties than its counterparts. The average and highest carrier mobility of the 70 air-exposed C8-BTBT TFTs were 4.82 and 8.07 cm 2 V -1 s -1 , respectively. This can be compared to 2.76 cm 2 V -1 s -1 and 4.70 cm 2 V -1 s -1 , respectively, for the 70 devices kept in HV. Furthermore, device air stability was investigated. The electrical performance of C8-BTBT TFTs degrades after long periods of air exposure. Our work improves knowledge of charge transport behavior and mechanisms in C8-BTBT OTFTs. It also provides ideas that may help to improve device electrical performance further.

The Sn-doped In 2 O 3 transparent conductive [indium tin oxide (ITO)] electrode in planar perovskite solar cells (PSCs) is modified by a zirconia (ZrO 2 ) interlayer with a low-temperature process. Here, the ZrO 2 film is prepared by ultraviolet (UV) treatment at room temperature. The effects of the inserted ZrO 2 interlayer on the performance of CH 3 NH 3 PbI 3−x Cl x -based PSCs have been systemically studied. After optimizing the process, the champion efficiency of PSCs with a UV-treated ZrO 2 interlayer is 19.48%, which is larger than that of the reference PSC (15.56%). The improved performance in the modified devices is primarily ascribed to the reduced trap states and the suppressed carrier recombination at the ITO/SnO 2 interface. Our work provides a facile route to boost the photovoltaic performance of PSCs by modifying the surface of the transparent conductive electrode at room temperature. KEYWORDS: ITO/SnO 2 interface modification, room-temperature processed ZrO 2 interlayer, ultraviolet (UV) treatment, planar perovskite solar cell, photoelectric properties

Low temperature fabrication of high quality dielectric films for high performance flexible electronics is still a big challenge. In this work, we realized low temperature fabrication of high quality amorphous ZrO2 dielectric films via a low-cost solution process. The microstructure and electrical properties, as well as the electronic structures of solution processed ZrO2 films have been investigated systematically. The ZrO2 films with 160 °C annealed showed a low leakage current (3.6  ×  10−5 A cm−2 at  −3 V) and a high band gap (5.4 eV). The flexible organic thin film transistor (OTFT) made by using the solution-processed amorphous ZrO2 dielectric shows a low operation voltage of 4 V and a high drain current on/off ratio of 2.4  ×  105. The frequency response of the ZrO2-OTFT device is up to 51.8 KHz under a low gate voltage of  −3 V. Our work demonstrated that a solution processable ZrO2 film is promising for applications in future low power consumption and wearable flexible electronic devices.

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