Abdi-Jalebi Mojtaba, Andaji-Garmaroudi Zahra, Pearson Andrew J, Divitini Giorgio, Cacovich Stefania, Philippe Bertrand, Rensmo Håkan, Ducati Caterina, Friend Richard H, Stranks Samuel D
Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge CB3 0HE, United Kingdom.
Department of Materials Science & Metallurgy, University of Cambridge, Cambridge CB3 0FS, United Kingdom.
ACS Energy Lett. 2018 Nov 9;3(11):2671-2678. doi: 10.1021/acsenergylett.8b01504. Epub 2018 Sep 28.
Halide perovskites passivated with potassium or rubidium show superior photovoltaic device performance compared to unpassivated samples. However, it is unclear which passivation route is more effective for film stability. Here, we directly compare the optoelectronic properties and stability of thin films when passivating triple-cation perovskite films with potassium or rubidium species. The optoelectronic and chemical studies reveal that the alloyed perovskites are tolerant toward higher loadings of potassium than rubidium. Whereas potassium complexes with bromide from the perovskite precursor solution to form thin surface passivation layers, rubidium additives favor the formation of phase-segregated micron-sized rubidium halide crystals. This tolerance to higher loadings of potassium allows us to achieve superior luminescent properties with potassium passivation. We also find that exposure to a humid atmosphere drives phase segregation and grain coalescence for all compositions, with the rubidium-passivated sample showing the highest sensitivity to nonperovskite phase formation. Our work highlights the benefits but also the limitations of these passivation approaches in maximizing both optoelectronic properties and the stability of perovskite films.
与未钝化的样品相比，用钾或铷钝化的卤化物钙钛矿表现出优异的光伏器件性能。然而，尚不清楚哪种钝化途径对薄膜稳定性更有效。在此，我们直接比较了用钾或铷物种钝化三阳离子钙钛矿薄膜时薄膜的光电特性和稳定性。光电和化学研究表明，合金化的钙钛矿对钾的负载量比铷更耐受。钾与钙钛矿前驱体溶液中的溴化物络合形成薄的表面钝化层，而铷添加剂有利于形成相分离的微米级卤化铷晶体。这种对较高钾负载量的耐受性使我们能够通过钾钝化实现优异的发光性能。我们还发现，暴露在潮湿气氛中会导致所有成分发生相分离和晶粒合并，其中铷钝化样品对非钙钛矿相形成的敏感性最高。我们的工作突出了这些钝化方法在最大化钙钛矿薄膜的光电特性和稳定性方面的优点和局限性。
