Photophysical Characterization of Layered Perovskites for Solar Cell Applications
Lisanne Einhaus is a PhD student in the Photocatalytic Synthesis group. (Co)Promotors are dr. ir. J. M. Huijser and prof. dr. G. Mul from the Faculty of Science & Technology.
The transition to renewable energy is crucial in combating global warming, with solar power offering a key solution. While silicon-based solar cells dominate the market, ongoing research explores new materials that could enhance efficiency and reduce costs.
Among these materials, quasi-two-dimensional (quasi-2D) metal halide perovskites have emerged as promising candidates due to their impressive optical and optoelectronic properties. Compared to their three-dimensional (3D) counterparts, quasi-2D perovskites offer improved stability. In quasi-2D metal halide perovskite (MHP) films, large organic cations, known as spacer molecules, separate the inorganic layers, forming domains of varying thicknesses, referred to as n-phases. The coexistence of multiple n-phases within a single quasi-2D film leads to complex photoinduced exciton and charge carrier dynamics, which directly impact the solar cell performance.
In photovoltaic (PV) devices, maximizing efficiency depends on the rapid extraction of photoexcited charge carriers before they recombine through either radiative (photon-emitting) or non-radiative (trap-assisted) pathways. However, in quasi-2D perovskites, the presence of different n-phases introduces additional complexity. Each domain exhibits a distinct bandgap, affecting how excitons (bound electron-hole pairs) and free charge carriers behave. Factors such as crystal composition, structure, orientation, and defects significantly influence these photophysical processes. Despite the potential of quasi-2D perovskites, existing photophysical models struggle to fully explain their exciton and charge carrier dynamics, and interpretations often remain inconsistent.
This research aims to deepen our understanding of photoinduced exciton and charge carrier dynamics in quasi-2D perovskites. By investigating hot carrier thermalization, the directionality and time scales of transfer processes between low-n and high-n phases, and whether these involve excitons or charge carriers, this work aims to pave the way for optimizing quasi-2D perovskites for PV applications. Ultimately, these insights will contribute to the development of high-efficiency and stable PV technologies.
