Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
DOI: https://doi.org/10.29363/nanoge.hopv.2022.086
Publication date: 20th April 2022
Hybrid metal-halide perovskite materials are ideally suited for photovoltaic energy conversion thanks to the strong optical absorption and remarkably low non-radiative recombination which allows perovskite solar cell devices to operate close to the radiative limit[1]. In addition, these materials feature a sharp absorption edge[2] with a pronounced overlap of absorption and intrinsic emission spectra. All these properties together lead to non-negligible photon recycling effects[3], [4], with a positive influence on device performance, such as an increase in open-circuit voltage[5].
In order to predict such photon recycling effects it is crucial to rigorously model the coupled optical and electronic processes in realistic thin-film device architectures. While the electronic transport processes are described using a well-established drift-diffusion algorithm including the effects of mobile ions[6], [7] implemented in the simulation software SETFOS, the optical absorption and emission rates are modeled using novel general expressions based on the photonic Green’s function theory in multilayer structures[8], [9].
The optical model provides the local reabsorption rate as well as a detailed-balance compatible radiative prefactor which are used in the electronic model to achieve a self-consistent solution that yields the full optoelectronic device characteristics.
Applying our model to a full methylammonium lead iodide (MAPI) solar cell stack, we are now able for the first time to simulate the full JV curve with and without photon recycling taken into account. A clear VOC enhancement of ∼35 mV is visible when reabsorption is considered. In case of an ideal structure of a pure MAPI absorber with ideally selective contacts, this enhancement increases to ∼55 mV, which is close to the estimate based on pure optical considerations.
The global efficiency of photon recycling is quantified by defining quantum efficiencies of reabsorbed radiation, while the local efficiency can furthermore be quantified by defining an effective local radiative prefactor. The model introduced here can be used to guide the design of future devices that exploit the full potential of photon recycling.