Our research activities are grouped into 2 categories.

 

Characterization:

Our main strength is the characterization of solar cells. Here, we focus foremost on understanding ionic degradation loss mechanisms, e.g., understanding the mobile ion density evolution during device aging and how this determines the stability of perovskite cells. We use several innovative electro-optical measurements, especially "fast-hysteresis" (scan-rate-dependent) JV characterization, as well as charge extraction and capacitance-based measurements.

 

More broadly, we aim to decouple key recombination losses under different environmental stressors using various electro-optical measurements, such as PL spectroscopy.

 

We also utilize AI and machine learning models to gain more insights into the degradation losses. Understanding the underlying degradation mechanisms may, in turn, help us in the future to predict the stability of devices and quickly identify perovskite compositions.

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  Device development:

A major goal of our activities is the development of stable perovskite-based tandem solar cells. Therefore, we focus on wide-bandgap perovskite devices, which typically suffer from halide segregation leading to instabilities. However, our recent perovskite formulations based on pure-iodide perovskite now lead to greatly improved operational lifetimes with excellent phase stability (see publications). We also work on implementing improved transport layers to improve extraction and minimize interfacial recombination losses. For example, we recently implemented highly stable self-assembled monolayers that can overcome the long-standing challenge of reverse-bias breakdown in perovskite PV (see publications).

 

In addition to compositional and transport engineering, we develop ultra-light flexible perovskite photovoltaics, with the long-term goal of developing space PV to power satellites or future space missions. In 2027, we will launch the first perovskite cells into low Earth orbit.

 

Moreover, we aim to utilize such flexible perovskite solar cells in sensor applications such as IoT sensors, as well as wearable biomedical health sensors, in collaboration with Prof. Ni Zhao from EE. 

 

Furthermore, we also utilize perovskite for detector and imaging applications, such as X-ray detectors, where perovskites have unique advantages. Finally, to advance organic/perovskite ultra-thin tandem solar cells, we study loss mechanisms of low-bandgap organic semiconductors and associated solar cells with state-of-the-art performances.