Research Paper: Hot carrier dynamics in operational metal halide perovskite solar cells
Scientific Summary
This study investigates the hot carrier relaxation dynamics in operational triple halide perovskite solar cells using high-power transient absorption (TA) measurements under various bias conditions (open circuit, short circuit, and maximum power point) and illumination directions. The main goal was to deconvolve the underlying physics of carrier thermalization close to real-world operating conditions. Key findings reveal a complex interaction involving carrier density, transport, and extraction. Higher hot carrier temperatures (Tc, >4000 K) were observed at high power densities. Front-side illumination resulted in higher Tc compared to back-side, attributed to greater photon absorption in the perovskite layer. Notably, Tc was lowest under short-circuit current (Jsc) conditions, indicating efficient carrier extraction enhances thermalization. Thermalization time was faster with front-side illumination, yet carrier lifetime was longer under back-side illumination, possibly due to hot carriers generated in the C60 electron transport layer. These dynamics are modulated by external bias and excitation direction.
Why it Matters
This research provides crucial in-operando insights into hot carrier dynamics, addressing thermalization losses—the largest loss mechanism (~35%) in solar cells. By understanding how operating conditions influence hot carrier behavior, the study offers a pathway to rationally design high-efficiency (potentially >60% PCE for single-junction) and stable perovskite solar cells. These findings are essential for advancing hot carrier solar cell technology, making it closer to practical application.
Publication Details
Afshari, H., Mapara, V., Sourabh, S., Khanal, M. N., Whiteside, V. R., Scheidt, R. A., Beard, M. C., Eperon, G. E., Sellers, I. R., & Furusa, M. (2025), Hot carrier dynamics in operational metal halide perovskite solar cells. EES Solar. DOI: 10.1039/d5el00063g. Received 23rd April 2025, Accepted 15th July 2025.
Fluxim Tools Used
The Setfos software (Fluxim) was utilised for simulations of the layer absorbance profile of the solar cells. Specifically, Setfos, which uses the transfer matrix formalism, was employed to model the structure under front and back side illumination. This helped to understand the different photon transmission rates through various layers, which explained why different carrier densities and hot carrier temperatures were observed depending on the illumination direction. This benefit highlights Setfos's utility in providing crucial optical insights for experimental interpretation.