In Situ Formation of Mixed-Dimensional Surface Passivation Layers in Perovskite Solar Cells with Dual-Isomer Alkylammonium Cations.

Dimensional engineering of perovskite solar cells has attracted significant research attention recently because of the potential to improve both device performance and stability. Here, a novel 2D passivation scheme for 3D perovskite solar cells is demonstrated using a mixed cation composition of 2D perovskite based on two different isomers of butylammonium iodide. The dual-cation 2D perovskite outperforms its single cation 2D counterparts in surface passivation quality, resulting in devices with an impressive open-circuit voltage of 1.

Polymer Electrolyte Blend Gate Dielectrics for High-Performance Ultrathin Organic Transistors: Toward Favorable Polymer Blend Miscibility and Reliability.

We report on systematic mobility enhancements in electrolyte-gated organic field-effect transistors (OFETs) by thinning down the active layer and exploiting polymer solid-state electrolyte gate insulators (SEGIs). The SEGI is composed of homogeneous poly(vinylidene fluoride- co-hexafluoropropylene) [P(VDF-HFP)] polymer solution-ion gel blends of high areal capacitance of >10 μF cm at 1 Hz. By scaling up the poly(3-hexylthiophene) (P3HT) semiconducting layer by 1 order of magnitude (5-50 nm), an ultraviolet photoelectron spectroscopy examination reveals a downward vacuum-level shift generating a substantial hole injection barrier that originates from different interfacial dipole layer formations.

Ultrahigh Mobility in Solution-Processed Solid-State Electrolyte-Gated Transistors.

A new concept of a high-capacitance polymeric dielectric based on high-k polymer and ion gel blends is reported. This solid-state electrolyte gate insulator enables remarkable field-effect mobilities exceeding 10 cm V s for common polymer and other semiconductor families at V ≤ 2 V owing to high areal capacitance (>4 µF cm ) from combined polarization of CF interface dipoles and electrical-double-layer formation.

Highly Sensitive Flexible NH Sensors Based on Printed Organic Transistors with Fluorinated Conjugated Polymers.

Understanding the sensing mechanism in organic chemical sensors is essential for improving the sensing performance such as detection limit, sensitivity, and other response/recovery time, selectivity, and reversibility for real applications. Here, we report a highly sensitive printed ammonia (NH) gas sensor based on organic thin film transistors (OTFTs) with fluorinated difluorobenzothiadiazole-dithienosilole polymer (PDFDT). These sensors detected NH down to 1 ppm with high sensitivity (up to 56%) using bar-coated ultrathin (<4 nm) PDFDT layers without using any receptor additives.