Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife KY16 9SS, United Kingdom.
Organic Semiconductor Centre, EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom.
J Phys Chem Lett. 2023 Mar 30;14(12):3007-3013. doi: 10.1021/acs.jpclett.3c00082. Epub 2023 Mar 21.
Charge diffusion and extraction are crucial steps in the operation of solar cells. Here we show that time-resolved photoluminescence can be used to study electron diffusion in hybrid perovskite films and subsequent transfer to the adjacent electron extraction layer. As diffusion and transfer to the extraction layer are consecutive processes, they can be hard to distinguish, but by exciting from each side of the sample we can separate them and identify which process limits charge extraction. We find that the introduction of a fullerene monolayer between the methylammonium lead iodide (MAPbI) and the electron-transporting SnO layers greatly increases the electron transfer velocity between them to the extent that electron diffusion limits the rate of electron extraction. Our results suggest that increasing the electron diffusion coefficient in MAPbI would further enhance the electron extraction rate, which could result in more efficient n-i-p type solar cells.
电荷扩散和提取是太阳能电池运行的关键步骤。在这里，我们展示了时间分辨光致发光可用于研究混合钙钛矿薄膜中的电子扩散以及随后向相邻的电子提取层的转移。由于扩散和向提取层的转移是连续的过程，因此很难区分，但通过从样品的两侧激发，我们可以将它们分开，并确定哪个过程限制了电荷提取。我们发现，在甲基碘化铵铅（MAPbI）和电子传输 SnO 层之间引入富勒烯单层会大大增加它们之间的电子转移速度，以至于电子扩散限制了电子提取的速率。我们的结果表明，增加 MAPbI 中的电子扩散系数将进一步提高电子提取速率，从而使 n-i-p 型太阳能电池更有效率。
