Bicolour, large area, inkjet-printed metal halide perovskite light emitting diodes†

We demonstrate a bicoloured metal halide perovskite (MHP) light emitting diode (LED) fabricated in two sequential inkjet printing steps. By adjusting the printing parameters, we selectively and deliberately redissolve and recrystallize the first printed emissive layer to add a pattern emitting in a different color. The red light emitting features (on a green light emitting background) have a minimum size of 100 μm and originate from iodide-rich domains in a phase-segregated, mixed MHP. This phase forms between the first layer, a bromide-based MHP, which is partially dissolved by printing, and the second layer, an iodide-containing MHP. With an optimised printing process we can retain the active layer integrity and fabricate bicolour, large area MHP-based LEDs with up to 1600 mm2 active area. The two emission peaks at 535 nm and 710 nm are well separated and produce a strong visual contrast.Bundesministerium für Bildung und Forschung 10.13039/501100002347Helmholtz Energy Materials Foundry 10.13039/501100015608Peer Reviewe

Large area inkjet-printed metal halide perovskite LEDs enabled by gas flow assisted drying and crystallization

We demonstrate the upscaling of inkjet-printed metal halide perovskite light-emitting diodes. To achieve this, the drying process, critical for controlling the crystallization of the perovskite layer, was optimized with an airblade-like slit nozzle in a gas flow assisted vacuum drying step. This yields large, continuous perovskite layers in light-emitting diodes with an active area up to 1600 mm2.Peer Reviewe

Reconciling risk sharing with market discipline: a constructive approach to euro area reform

The euro area continues to suffer from critical weaknesses that are the result of a poorly designed fiscal and financial architecture, but its members are divided on how to address the problems. This paper proposes six reforms which, if delivered as a package, would improve the euro area’s financial stability, political cohesion, and potential for delivering prosperity to its citizens, all while addressing the priorities and concerns of participating countries

COVID-19 economic crisis : Europe needs more than one instrument

Published 05 April 2020There are now several proposals for complementing the vigorous decision of the ECB to launch a mega ‘pandemic emergency purchase programme’ with fiscal and financial initiatives at the European level. These proposals sometimes overlap, which is a good sign of convergence. This column argues that they are also largely complementary to one another. Hence, it calls for a multi-instrument approach that would jointly achieve three objectives: sharing the cost of the COVID crisis, helping member states to borrow at very long maturities and low interest rates, and relaunching the EU after the crisis. In addition to existing tools, the authors believe that a tryptic built around a COVID fund (with borrowing capacity), specific credit guarantees with the European Investment Bank and dedicated credit lines such as an ESM COVID line or the recently proposed temporary Support to mitigate Unemployment Risks in an Emergency (SURE) would be appropriate, provided it is sized up and allows for very long-run borrowing