In Situ Analysis Reveals the Role of 2D Perovskite in Preventing Thermal-Induced Degradation in 2D/3D Perovskite Interfaces.

Albertus A Sutanto,Ana Flavia Nogueira,P E Marchezi,Rodrigo Szostak,Nikita Drigo,Hélio C N Tolentino,Mohammad Khaja Nazeeruddin,Giulia Grancini,J C Germino,Valentin I E Queloz

doi:10.1021/acs.nanolett.0c01271

Abstract

Engineering 2D/3D perovskite interfaces is a common route to realizing efficient and stable perovskite solar cells. Whereas 2D perovskite’s main function in trap passivation has been identified and is confirmed here, little is known about its 2D/3D interface properties under thermal stress, despite being one of the main factors that induces device instability. In this work, we monitor the response of two typical 2D/3D interfaces under a thermal cycle by in situ X-ray scattering. We reveal that upon heating, the 2D crystalline structure undergoes a dynamical transformation into a mixed 2D/3D phase, keeping the 3D bulk underneath intact. The observed 3D bulk degradation into lead iodide is blocked, revealing the paramount role of 2D perovskite in engineering stable device interfaces.

Highlights

Engineering 2D/3D perovskite interfaces is a common route to realizing efficient and stable perovskite solar cells
2D perovskites simultaneously act as a surface defect passivant layer and retard charge recombination at the interface with a positive effect on device open-circuit voltage.[21−30] On top, as previously mentioned, 2D perovskites show high humidity resilience due to their increased chemical stability and hydrophobicity, which slows down device degradation.[31−34] so far, little is known about the role of 2D perovskite upon thermal stress, which is a recognized cause of perovskite device degradation
They consist of a bulky thiophene- or phenyl-terminated cations in the form of 2-thiophenemethylammonium iodide (2-TMAI) or phenylethylammonium (PEAI), forming (2-TMAI)2PbI4 and PEA2PbI4 2D perovskites, respectively, which overlayer the bulk 3D perovskite. (See Figure 1a.) The structural evolution of the interface is monitored upon exposing the sample to a thermal cycle, simulating the working conditions under real device operation

Summary

Introduction

Engineering 2D/3D perovskite interfaces is a common route to realizing efficient and stable perovskite solar cells. Whereas the main focus was the study of the interface structural modification, we fabricated 2-TMAI-2D/3D and PEAI-2D/3D solar cells, and we tested them upon the same thermal cycle as that used for the in situ measurements.

Results

Conclusion