Ternary blend halide perovskites for light emission and detection

Introduction

Perovskite lasers are on the verge of showing stimulated emission not only by optical pumping but also by purely electrical excitation[1], [2], [3]. Passing that milestone, this technology can provide fully wafer integrated light sources and amplifiers. While thin film processes enable high speed large area coatings, vacuum deposition increases the composition control in the vertical stack direction. In contrast to standard solution processes, vacuum technology can produce films with higher purity and enables the controlled manufacturing of heterojunctions. This allows for the fabrication of new diode architectures on the route to optimize the electronic and optical properties for the next generation of perovskite lasers, light emitting diodes and photodetectors. Ultimately, such thin film diodes can be the light sources and light detectors in photonic integrated circuits, or they can be applied in large areas for surface emitting lasers or image detectors opening new application tracks. In the proposed PhD project, we want to explore the composition parameter space of binary and ternary blends of halide perovskite systems.

The material composition of CsPbBr₃ has been presented as an excellent gain medium with respect to lasing threshold in a wide range of implementations[3]. With a modification of the halide content by introducing Cl and/or I ions and varying the ratios within this ternary system, the film properties including the electronic bandgap can be tuned which results in changes of emission wavelength, gain bandwidth and threshold [4]. It is the goal of this work to identify optimum parameter sets and processing conditions for light emitting and light detection devices with a dedicated view on high system performance and long stability.

Within an unprecedented short time, lead halide perovskites have been proven to be viable candidates for active materials in future optoelectronic devices. They show extraordinary performance as gain media in thin film lasers and withstand extremely high current densities under electrical pumping[1] as well as active materials in ultrafast photodiodes for color imagers[5] . At imec, we produce state-of-the-art perovskite devices from solar cells to thin film lasers that we can investigate in sophisticated electro-optical characterization setups to gain a deeper understanding.

It is the goal of this PhD, to combine material knowledge, chemistry and physics to optimize perovskite films for a wide range of applications from photodetectors to perovskite laser diodes with their specific performance requirement and a special view on stability.

Topic

This PhD is highly experimental and consists of two parts: thin film device fabrication and characterization. You feel comfortable in a lab environment working with vacuum processes and you are familiar with electrical and optical characterization tools. Overall, you are curious and motivated to explore the fascinating world of thin film optoelectronic devices for light detection and light emission with their wide range of potential applications – all this in the environment of a leading research institution. Together we define the relevant target parameters to ensure an efficient development process.

At all stages of the work, you can rely on the support of our highly skilled team of engineers and scientists.

The candidate

You have recently finished your studies with a master’s degree in material science, chemistry, semiconductor physics, nano-engineering, or related. You are highly motivated to dive with us into the world of thin film processing for optoelectronic devices. You are a hands-on person in a lab environment and have creativity that helps you in problem solving and data analysis. You are a team player and have good communication skills as you will work in a multidisciplinary and multicultural team. You have the chance to regularly present your results thus getting guidance and feedback from our team. Given the international character of imec and the KU Leuven, an excellent knowledge of English is a must.