With the growing interest in haldide perovskite materials for modern photovoltaics and especially solar cells, a team led by researchers at ITMO University in St. Petersburg have shown how to improve the efficiency of perovskite solar cells using silicon nanoparticles to enhance their light harvesting properties. These dialectric nanoparticles are highly resonant, and work to trap the light of a range of wavelengths close to the cell active layer; as they can’t absorb light they don’t heat up, and are also chemically inert and so don’t interact with other parts of the battery, ensuring overall stability.
In terms of performance, it is important to provide advanced photon and charge carriers management to devices. Ideally, photon management requires full absorption of incoming light from the Sun, while the best charge carrier management is full efficiency of the harvesting of the generated charges while avoiding their parasitic recombination at defects in the perovskite layer. However, to improve absorption it is usually key to make the perovskite layer thicker, which increases the length of the charges propagation to the electrodes, bringing more harmful interactions with defects.
“The proposed approach is quite universal and can improve not only to standard non-optimized perovskites, but also for the more stable and well-performing perovskites with complicated compositions”Sergey Makarov
Silicon nanoparticles enhance cell efficiency by nearly 19%This led to the team looking at whether it was possible to increase absorption without changing the thickness. Nanoantennas can be used to trap light within the perovskite thin layer, and previous studies have incorporated metallic nanoparticles into perovskite solar cells, but their metallic origin always leads to quenching of the electron-hole pair touching their surface. However, as reported in Advanced Optical Materials [Furasova et al. Adv. Opt. Mater. (2018) DOI: 10.1002/adom.201800576], here they managed to completely change the concept by replacing metallic nanoantennas with silicon ones.
The silicon versions can still efficiently trap the light at nanoscale, but do not increase parasitic recombination of the charges. The integration of the resonant silicon nanoparticles into perovskite solar cells brought record values of efficiency for such a perovskite material with incorporated nanoparticles, as the layout characteristics enhanced the cells efficiency by nearly 19%.
The team hope that a greater knowledge of the interaction between nanoparticles and light, and their application in perovskite solar cells, will improve results even more. The nanoparticles could also be used for other types of perovskites with increased efficiency and stability, and the particles themselves – which are inexpensive and easy to produce – can be also be modified to enhance their optical and transport properties. As Sergey Makarov told Materials Today, “The proposed approach is quite universal and can improve not only to standard non-optimized perovskites, but also for the more stable and well-performing perovskites with complicated compositions”.