Surface and Interface Defects can Control Bulk Doping in Polycrystalline Pb-Halide Perovskites
david cahen a, antoine kahn b
a Dept. of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 7610015, Israel
b Department of Electrical and Computer Engineering, Princeton University, Princeton, NJ 08544, United States
Invited Speaker Session, david cahen, presentation 099
Publication date: 6th February 2024

Doping, controlled “electronic contamination” of semiconductors, allows to regulate the electronic behavior inside the semiconductor. Metal halide perovskite (HaP) materials, the functional materials of several types of optoelectronic devices, challenge our understanding of semiconductors. We show that, for HaPs, the control of doping type and density and properties derived from these is, to a first approximation, via their surfaces (some of which will become part of their interfaces with electrodes), i.e., defects with energy levels within the bandgap (EG). These defects can impact and even dominate bulk electrical and electronic HaP properties and, ultimately, the device performance.

While such effect can be relevant to all semiconductors, it is dominant in HaPs because of their intrinsically low densities of electrically active bulk and surface defects. Even for most polycrystalline (< 1 mm grain diameter) thin HaP films, the volume carrier densities (cm-3) deduced from experiments are below those that result if even < 0.1% of surface sites function as electrically active defects (for the bulk grain). A direct implication is that interface defects will control HaP-based devices, as those consist of multi-layered polycrystalline structures with two interfaces with the HaP layer, where the action is. While surface/interface passivation effects on bulk electrical properties are relevant to all semiconductors and have been crucial for developing each current semiconductor technology, they are even more important for HaPs because bulk doping at electronics-relevant densities has turned out to be so difficult, certainly by established methods.


We thank Yevgeny Rakita for stimulating, fruitful discussions.  At the Weizmann Institute of Science (DC) the work received support from the Minerva Centre for Self-Repairing Systems for Energy & Sustainability and the Sustainability and Energy Research Initiative, SAERI.


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