LiU

Light-emitting diodes (LEDs) based on organometallic halide perovskites have attracted increasing interest due to their unique properties, such as high colour purity, easily tunable optoelectronic properties, and solution processable for low-cost and large-arear manufacturing, showing great potential in displays and lighting applications. Even though the photonic and electronic properties of perovskites are very attractive, the poor stability and relatively low photoluminescent efficiency are two major problems that limit their progress in LEDs. In this project, I aim to address these challenges and develop efficient and stable perovskite LEDs. I propose a) to design and synthesize Ruddlesden-Popper perovskite (RPP) emitters with stable crystal structures and excellent optoelectronic properties, with the help of first-principles calculations, b) to deposit high-quality RPP films using new synthetic routes, and c) to fabricate efficient and stable LEDs with performance beyond the state of the art, by coupling device engineering with device physics investigations. This project will increase the fundamental knowledge concerning RPP materials and devices. The expected outcomes are new type perovskite materials with good optoelectronic properties, as well as stable and efficient LEDs. In addition, I will be trained to develop new interdisciplinary knowledge and skills and to reach professional maturity by implementing the project. In addition to individual development, successful implementation of this project will also promote the international competitiveness of the host organization on research of perovskite optoelectronics. Potential commercialization of the new perovskite materials and LEDs products will also generate economic growth and new job opportunities for the Europe society.

Towards demonstrating new electrically pumped lasers based on the emerge metal halide perovskite, it is necessary to sandwich the perovskite thin film into transport layers for the integration of electrical devices. However, it is challenging to maintain the low threshold when introducing transport layers. The appearance of perovskite/transport layer interfaces, which is absent in most optically pumped perovskite lasers, is even considered as detrimental factors to lasing actions. By carefully integrating the perovskite films into electrical device structures, though reaching very high injection current densities (> 1 kA/cm2), often fails to realize lasing actions. The next urgent milestone towards electrically pumped perovskite lasers would be realization of low threshold when incorporating transport layers. This project has the goal to reduce lasing threshold of perovskite devices through transport layer engineering, a strategy which is the key step towards realizing perovskite lasers. I will take a holistic approach, where two novel strategies are proposed independently. Two objectives will contribute to solve an important challenge on interface engineering towards electrically pumped perovskite lasers. Objective 1: To reduce the surface recombination loss for low threshold. I will seek effective approaches to passivate perovskite films through transport layer engineering, leading to suppressed radiative and nonradiative recombination loss at perovskite boundaries. Objective 2: To reduce recombination loss channels caused by hot carriers for low threshold. I will achieve this objective by hot carrier management via selective transport layers, aiming at suppressing hot carrier injection and facilitating hot carrier cooling.

High embryonic mortality at the peri-implantation period (70%) is accounted after pig embryo transfer (ET), which is almost double than that of natural breeding or artificial insemination (AI). Since pregnancy is an interesting immunological paradox, our starting hypothesis is that the mechanisms regulating the maternal immune response to the embryos may be less efficient in the case of ET pregnancies, where the transferred embryos are allogeneic (e.g. contain paternal and maternal material unrelated to the recipient mother) than after natural breeding or AI, where only paternal material is unrelated to the mother (semi-allogeneic). This difference could be behind the increased embryonic death. The project will study transcriptomic and cytokine changes of porcine endometrial tissue in the presence of semi-allogeneic and allogeneic embryos during the peri-implantation period and also in the placenta of healthy and arrested fetuses. The results of the project will unveil mechanisms behind embryo-maternal dialogue. This fact is relevant in view of the necessary implementation of emergent breeding technologies, as embryo transfer (ET), for supporting sustainability and competitiveness of the European pig sector. EU is currently second biggest pig producer in the world and the largest exporter of antibiotic- and residue-free pig products derived from animals raised on highest welfare standards and with the highest genetic value. The understanding of embryo-maternal dialogue under allogeneic environments might be determinant to implement new strategies to increase the reproductive performance after ET not only in pigs but also, comparatively, in other livestock species and even in humans, where the use of donor oocytes for IVF is currently increasing. This project, with a focus on pregnancy immunological regulation, is of utmost interest for the EU goals, contributing to determine which factors still jeopardize full fertility and prolificacy when applying ET technology.