Interfacial Engineering and Recombination Kinetics in All-Evaporated, Lead-Free Perovskite Photodetectors for Next-Generation Advanced Imaging

High-performance thin-film photodetectors operating across broadband spectral regimes are crucial building blocks for next-generation technological applications, including machine vision, industrial automation, environmental sensing, and high-density imaging matrices. While conventional lead-based halide perovskites have achieved remarkable external quantum efficiencies (EQE) at low operational biases, severe heavy-metal toxicity barriers and strict environmental regulations hinder their widespread commercial adoption in mainstream consumer electronics foundries. Consequently, developing environmentally friendly, lead-free alternative thin-film absorbers represents an urgent mandate for the image sensor industry.

Our research group specializes in the synthesis and optimization of all-inorganic perovskite optoelectronic devices deposited entirely via multi-source dry-vacuum physical vapor deposition (co-evaporation). This completely solvent-free processing pipeline ensures sub-nanometer thickness control, superior structural purity, and cross-wafer uniformity, matching the rigorous integration requirements of large-area silicon electronics.

While our group has successfully established high-performance visible-light photodetectors using standard inorganic stacks utilizing symmetric carrier-selective transport layers, migrating this architecture to newly developed lead-free light absorbers introduce distinct electronic and interfacial challenges. Currently, vertical lead-free p-i-n photodiode configurations face critical carrier collection barriers. High background leakage currents in the dark narrow the photo-to-dark current modulation window, while non-radiative recombination at unpassivated interfaces caps the external quantum efficiency.

The objective of this Master’s thesis/internship project will be to systematically re-engineer the optoelectronic device stack to suppress these parasitic leakage pathways and maximize charge extraction efficiency. The selected candidate will focus on executing systematic electrical, optical, and junction-capacitance measurements to benchmark detector characteristics (including dark current density, spectral responsivity, transient photoresponse, and trap states). Utilizing this empirical data, the student will drive targeted process optimization loops to refine the structural and morphological quality of the active layer, alongside exploring advanced device optimization strategies such as alternative transport barriers and contact interfaces to passivate surface traps.

Following a short initial training period, the candidate will be able to work independently in a state-of-the-art cleanroom fabrication facility and an advanced electro-optical characterization laboratory, managing device processing and testing from start to finish. An international team of experienced researchers at imec will be present to provide continuous support and technical guidance.

The ideal candidate is a highly motivated, hands-on individual in a laboratory environment with a strong foundational background in solid-state device physics, photonics, or materials science, coupled with a proven record of analytical problem-solving and clean data interpretation. Given the international and collaborative character of imec, an excellent working knowledge of English is a prerequisite.