Beneficial role of Europium into CsPbI3 perovskites
Alessandra Alberti a, Emanuele Smecca a, Ioannis Deretzis a, Giovanni Mannino a, Corrado Bongiorno a, Salvatore Valastro a, Salvatore Sanzaro a, Giuseppe Fisicaro a, Ajay Kumar Jena b, Youhei Numata b, Zhanglin Guo b, Tsutomu Miyasaka b, Corrado Spinella a, Antonino La Magna a
a Institute for Microelectronics and Microsystems (CNR-IMM), Zona Industriale - VIII Strada 5, Catania 95121, Italy
b Graduate School of Engineering Toin University of Yokohama 1614 Kurogane-cho, Aoba, Yokohama, Kanagawa 225-8503, Japan
International Conference on Hybrid and Organic Photovoltaics
Proceedings of International Conference on Hybrid and Organic Photovoltaics (HOPV22)
València, Spain, 2022 May 19th - 25th
Organizers: Pablo Docampo, Eva Unger and Elizabeth Gibson
Oral, Alessandra Alberti, presentation 034
Publication date: 20th April 2022

The orthorhombic gamma-phase of CsPbI3 is the photoactive Perovskite (PSK) with the simplest stoichiometry to be used in tandem with Silicon Solar Cells. It has an energy gap of 1.75-1.78 eV, well complementing the absorption range of a Silicon. In addition, it is a fully inorganic Perovskite that does not suffer from degradation through the formation of volatile species, and indeed the risk of mass loss during operation or during ageing is intrinsically prevented.

Nonetheless, bottlenecks on the use of gamma-CsPbI3 are the formation temperature that requires fast quenching from 320 °C and the intrinsic instability towards its non-photoactive yellow delta-polymorphism, both of which deserve special attention.

Herein, the convenient interplay between Eu incorporation and morphology to form the gamma-phase of CsPbI3 at 80 C (LT) is unveiled. In contrast, pure CsPbI3 without Eu is a mixture of gamma-phase and non-PSK delta-phase at 65 C or it is a fully delta-phase at 80 C.

Based on experimental and theoretical findings, we argued about a double beneficial role of Eu. On one hand, it assists in the formation of the gamma-phase either by substituting Pb or by occupying interstitial positions in the CsPbI3 lattice. On the other hand, it promotes the formation of a fine-grained layer at LT wherein the high surface-to-volume ratio makes the establishment of the delta-phase unfavourable. Strain accommodation in the fine-grained matrix and the formation of a gluing intergrain-self-material during the kinetics of reaction (snowplow effect) cooperate in extending the lifetime of the LT gamma-phase to ~40 h at 65 C compared to only ~10–15 min in the sample without Eu for the complete phase transformation.

The disclosed phenomena draw a method for the stabilization of the gamma-CsPbI3 phase that can be further exploited or improved,

This activity was partially supported at CNR by the national projects BEYOND NANO Upgrade (CUP G66J17000350007) and VertiGrow (CUP B15F21004410005). CNR also acknowledges the project PON entitled “Tecnologia per celle solari bifacciali ad alta Efficienza a 4 terminali per utility scale”, called BEST-4U, financed by the Italian Ministry MIUR (CUP B88D19000160005).

We use our own and third party cookies for analysing and measuring usage of our website to improve our services. If you continue browsing, we consider accepting its use. You can check our Cookies Policy in which you will also find how to configure your web browser for the use of cookies. More info