Increased Brightness and Reduced Efficiency Droop in Perovskite Quantum Dot Light-Emitting Diodes Using Carbazole-Based Phosphonic Acid Interface Modifiers.

We demonstrate the use of [2-(9-carbazol-9-yl)ethyl]phosphonic acid (2PACz) and [2-(3,6-di--butyl-9-carbazol-9-yl)ethyl]phosphonic acid (-Bu-2PACz) as anode modification layers in metal-halide perovskite quantum dot light-emitting diodes (QLEDs). Compared to conventional QLED structures with PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrenesulfonate)/PVK (poly(9-vinylcarbazole)) hole-transport layers, the QLEDs made with phosphonic acid (PA)-modified indium tin oxide (ITO) anodes show an over seven-fold increase in brightness, achieving a brightness of 373,000 cd m, one of the highest brightnesses reported to date for colloidal perovskite QLEDs. Importantly, the onset of efficiency roll-off, or efficiency droop, occurs at ∼1000-fold higher current density for QLEDs made with PA-modified anodes compared to control QLEDs made with conventional PEDOT:PSS/PVK hole transport layers, allowing the devices to sustain significantly higher levels of external quantum efficiency at a brightness of >10 cd m.

Thermally Stable Anthracene-Based 2D/3D Heterostructures for Perovskite Solar Cells.

Bulky organic cations are used in perovskite solar cells as a protective barrier against moisture, oxygen, and ion diffusion. However, bulky cations can introduce thermal instabilities by reacting with the near-surface of the 3D perovskite forming low-dimensional phases, including 2D perovskites, and by diffusing away from the surface into the film. This study explores the thermal stability of CsFAPbI 3D perovskite surfaces treated with two anthracene salts─anthracen-1-ylmethylammonium iodide (AMAI) and 2-(anthracen-1-yl)ethylammonium iodide (AEAI)─and compares them with the widely used phenethylammonium iodide (PEAI).

Manipulating Backbone Planarity of Ester Functionalized Conjugated Polymer Constitutional Isomer Derivatives Blended with Molecular Acceptors for Controlling Photovoltaic Properties.

Exploring both electron donor and acceptor phase components in bulk heterojunction structures has contributed to the advancement of organic photovoltaics (OPV) realizing power conversion efficiencies reaching 20%. Being able to control backbone planarity of the donor polymer, while understanding its effects on the polymer conformation and photophysical properties, fosters the groundwork for further achievements in this realm. In this report, three isomeric PM7 derivatives are designed and synthesized where the benzodithiophene-4,8-dione structure is replaced by a quaterthiophene bridge carrying two ester moieties.

Rationale and Challenges for a New Instrument for Remote Measurement of Negative Symptoms.

There is a broad consensus that the commonly used clinician-administered rating scales for assessment of negative symptoms share significant limitations, including (1) reliance upon accurate self-report and recall from the patient and caregiver; (2) potential for sampling bias and thus being unrepresentative of daily-life experiences; (3) subjectivity of the symptom scoring process and limited sensitivity to change. These limitations led a work group from the International Society of CNS Clinical Trials and Methodology (ISCTM) to initiate the development of a multimodal negative symptom instrument. Experts from academia and industry reviewed the current methods of assessing the domains of negative symptoms including diminished (1) affect; (2) sociality; (3) verbal communication; (4) goal-directed behavior; and (5) Hedonic drives.

Remote chirality transfer in low-dimensional hybrid metal halide semiconductors.

In hybrid metal halide perovskites, chiroptical properties typically arise from structural symmetry breaking by incorporating a chiral A-site organic cation within the structure, which may limit the compositional space. Here we demonstrate highly efficient remote chirality transfer where chirality is imposed on an otherwise achiral hybrid metal halide semiconductor by a proximal chiral molecule that is not interspersed as part of the structure yet leads to large circular dichroism dissymmetry factors (g) of up to 10. Density functional theory calculations reveal that the transfer of stereochemical information from the chiral proximal molecule to the inorganic framework is mediated by selective interaction with divalent metal cations.