Self-assembled monolayers (SAMs) based on Br-2PACz ([2-(3,6dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid) 2PACz ethyl]phosphonic acid) and ethyl]phosphonic acid) molecules were investigated as hole-extracting interlayers in organic photovoltaics (OPVs). The highest occupied molecular orbital (HOMO) energies of these SAMs were measured at À 6.01 and À 5.30 eV for Br-2PACz and MeO-2PACz, respectively, and found to induce significant changes in the work function (WF) of indium-tin-oxide (ITO) electrodes upon chemical functionalization. OPV cells based on PM6 (poly [(2,6-(4,8-bis(5-(2-ethylhexyl-3- ([6,6]-phenyl-C71-bu-tyric acid methyl ester) using ITO/Br-2PACz anodes exhibited a maximum power conversion efficiency (PCE) of 18.4 %, outperforming devices with ITO/MeO-2PACz (14.5 %) and ITO/poly (3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PE-DOT : PSS) (17.5 %). The higher PCE was found to originate from the much higher WF of ITO/Br-2PACz (À 5.81 eV) compared to ITO/MeO-2PACz (4.58 eV) and ITO/PEDOT : PSS (4.9 eV), resulting in lower interface resistance, improved hole transport/extraction, lower trap-assisted recombination, and longer carrier lifetimes. Importantly, the ITO/Br-2PACz electrode was chemically stable, and after removal of the SAM it could be recycled and reused to construct fresh OPVs with equally impressive performance.

Two-dimensional (2D) transition metal dichalcogenides (TMDs) nanoribbons are touted as the future extreme device downscaling for advanced logic and memory devices but remain a formidable synthetic challenge. Here, we demonstrate a ledge-directed epitaxy (LDE) of dense arrays of continuous, selfaligned, monolayer and single-crystalline MoS2 nanoribbons on β-gallium (III) oxide (β-Ga2O3) (100) substrates. LDE MoS2 nanoribbons have spatial uniformity over a long-range and transport characteristics on par with those seen in exfoliated benchmarks. Prototype MoS2 nanoribbon-based field-effect transistors exhibit high on/off ratios of 108 and an averaged room temperature electron

The influence of halogen substitutions (F, Cl, Br, and I) on the energy levels of the self‐assembled hole‐extracting molecule [2‐(9H‐Carbazol‐9‐yl)ethyl]phosphonic acid (2PACz), is investigated. It is found that the formation of self‐assembled monolayers (SAMs) of [2‐(3,6‐Difluoro‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (F‐2PACz), [2‐(3,6‐Dichloro‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (Cl‐2PACz), [2‐(3,6‐Dibromo‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (Br‐2PACz), and [2‐(3,6‐Diiodo‐9H‐carbazol‐9‐yl)ethyl]phosphonic acid (I‐2PACz) directly on indium tin oxide (ITO) increases its work function from 4.73 eV to 5.68, 5.77, 5.82, and 5.73 eV, respectively. Combining these ITO/SAM electrodes with the ternary bulk‐heterojunction (BHJ) system PM6:PM7‐Si:BTP‐eC9 yields organic photovoltaic (OPV) cells with power conversion efficiency (PCE) in the range of 17.7%–18.5%. OPVs featuring Cl‐2PACz SAMs yield the highest PCE of 18.5%, compared to cells with F‐2PACz (17.7%), Br‐2PACz (18.0%), or I‐2PACz (18.2%). Data analysis reveals that the enhanced performance of Cl‐2PACz‐based OPVs relates to the increased hole mobility, decreased interface resistance, reduced carrier recombination, and longer carrier lifetime. Furthermore, OPVs featuring Cl‐2PACz show enhanced stability under continuous illumination compared to ITO/PEDOT:PSS‐based cells. Remarkably, the introduction of the n‐dopant benzyl viologen into the BHJ further boosted the PCE of the ITO/Cl‐2PACz cells to a maximum value of 18.9%, a record‐breaking value for SAM‐based OPVs and on par with the best‐performing OPVs reported to date.

A nonfullerene acceptor, isoIDITC, capable of exhibiting fibril-like morphology, is utilized as a third component in organic photovoltaics (OPVs). A power conversion efficiency (PCE) of 19% is achieved in ternary...

Controlling the morphology of metal halide perovskite layers during processing is critical for the manufacturing of optoelectronics. Here, a strategy to control the microstructure of solution‐processed layered Ruddlesden–Popper‐phase perovskite films based on phenethylammonium lead bromide ((PEA)2PbBr4) is reported. The method relies on the addition of the organic semiconductor 2,7‐dioctyl[1]benzothieno[3,2‐b]benzothiophene (C8‐BTBT) into the perovskite formulation, where it facilitates the formation of large, near‐single‐crystalline‐quality platelet‐like (PEA)2PbBr4 domains overlaid by a ≈5‐nm‐thin C8‐BTBT layer. Transistors with (PEA)2PbBr4/C8‐BTBT channels exhibit an unexpectedly large hysteresis window between forward and return bias sweeps. Material and device analysis combined with theoretical calculations suggest that the C8‐BTBT‐rich phase acts as the hole‐transporting channel, while the quantum wells in (PEA)2PbBr4 act as the charge storage element where carriers from the channel are injected, stored, or extracted via tunneling. When tested as a non‐volatile memory, the devices exhibit a record memory window (>180 V), a high erase/write channel current ratio (104), good data retention, and high endurance (>104 cycles). The results here highlight a new memory device concept for application in large‐area electronics, while the growth technique can potentially be exploited for the development of other optoelectronic devices including solar cells, photodetectors, and light‐emitting diodes.

Ferroelectric tunnel junctions (FTJs) are ideal resistance‐switching devices due to their deterministic behavior and operation at low voltages. However, FTJs have remained mostly as a scientific curiosity due to three critical issues: lack of rectification in their current‐voltage characteristic, small tunneling electroresistance (TER) effect, and absence of a straightforward lithography‐based device fabrication method that would allow for their mass production. Co‐planar FTJs that are fabricated using wafer‐scale adhesion lithography technique are demonstrated, and a bi‐stable rectifying behavior with colossal TER approaching 106% at room temperature is exhibited. The FTJs are based on poly(vinylidenefluoride‐co‐trifluoroethylene) [P(VDF‐TrFE)], and employ asymmetric co‐planar metallic electrodes separated by <20 nm. The tunneling nature of the charge transport is corroborated using Simmons direct tunneling model. The present work is the first demonstration of functional FTJs manufactured via a scalable lithography‐based nano‐patterning technique and could pave the way to new and exciting memory device concepts.

The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes hinder their deployment in emerging radio frequency (RF) electronics. Here, these limitations are overcome by combining self‐aligned asymmetric nanogap electrodes (≈25 nm) produced by adhesion lithography, with a high mobility organic semiconductor, and RF Schottky diodes able to operate in the 5G frequency spectrum are demonstrated. C16IDT‐BT is used, as the high hole mobility polymer, and the impact of p‐doping on the diode performance is studied. Pristine C16IDT‐BT‐based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (fC) of >100 and 6 GHz, respectively. This extraordinary performance is attributed to the planar nature of the nanogap channel and the diode's small junction capacitance (<2 pF). Doping of C16IDT‐BT with the molecular p‐dopant C60F48 improves the diode's performance further by reducing the series resistance resulting to intrinsic and extrinsic fC of >100 and ≈14 GHz respectively, while the DC output voltage of an RF rectifier circuit increases by a tenfold. Our work highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large‐area RF electronics of the future.

Bismuth containing hybrid molecular ferroelectrics are receiving tremendous attention in recent years owing to their stable and non‐toxic composition. However, these perovskite‐like structures are primarily limited to ammonium cations. Herein, we report a new phosphonium based discrete perovskite‐like hybrid ferroelectric with a formula [Me(Ph)3P]3[Bi2Br9] (MTPBB) and its mechanical energy harvesting capability. The Polarization‐Electric field (P‐E) measurements resulted in a well‐defined ferroelectric hysteresis loop with a remnant polarization value of 2.1 μC cm−2. Piezoresponse force microscopy experiments enabled visualization of the ferroelectric domain structure and evaluation of the piezoelectric strain coefficient (d33) for an MTPBB single crystal and thin film sample. Furthermore, flexible devices incorporating MTPBB in polydimethylsiloxane (PDMS) matrix at various concentrations were fabricated and explored for their mechanical energy harvesting properties. The champion device with 20 wt % of MTPBB in PDMS rendered a maximum peak‐to‐peak open‐circuit voltage of 22.9 V and a maximum power density of 7 μW cm−2 at an optimal load of 4 MΩ. Moreover, the potential of MTPBB‐based devices in low power electronics was demonstrated by storing the harvested energy in various electrolytic capacitors.