Sakshi Sharma
Advisors: Prof. Antonio Facchetti, Prof. Juan-Pablo Correa-Baena

will propose a doctoral thesis entitled,

Tuning Mechanical Properties and Structural Stability of Perovskite Films and Devices via Spatial Confinement in Polymer Scaffolds

On

Friday, May 8 at 12 noon
MRDC Room 4211

and 

 Virtually via MS Teams 

https://teams.microsoft.com/meet/26823533789387?p=sV8kEfgejJ7c3gwyeR

Committee
             Prof. Antonio Facchetti, Co-advisor, School of Materials Science and Engineering

Prof. Juan-Pablo Correa-Baena, Co-advisor, School of Materials Science and Engineering

Prof. Natalie Stingelin, School of Materials Science and Engineering

Prof. Seung-Soon Jang, School of Materials Science and Engineering

Prof. Tobin J. Marks, ChBE, Northwestern University

Abstract
Mechanical instability remains a critical challenge for perovskite solar cells (PSCs), limiting their applications in real-world, dynamic environments. This challenge primarily arises from the intrinsic brittleness of polycrystalline perovskite active layers, which are prone to cracking under impact and repeated mechanical deformations. Achieving mechanical compliance within the perovskite layer can enable sustained operation under large and repeated deformations, leading to applications that are not accessible to rigid films and devices, such as conformal and portable energy harvesters, soft robotic systems, and dynamically deformable electronics. This thesis aims to (a) develop mechanically flexible photoactive perovskite films and corresponding devices by confining the perovskite material into patterned polymeric scaffolds, and (b) study the role of scaffolds in influencing the crystal structure stability of embedded perovskite. The polymers used as the scaffold range from plastics to elastomers.

First, the effect of geometric confinement on phase stability and mechanical properties of patterned perovskite architectures is studied using functionalized cellulose scaffolds fabricated by lithography-free breath figure method. We discover that in addition to making perovskite mechanically compliant, perovskite incorporation into the polymeric matrix also improves its temperature and moisture stability, which can have broad implications in stabilizing rigid PSCs. Next, we will extend this approach to lithographically designing the scaffolds with plastic as well as elastomeric materials, hypothesizing that by tuning the scaffold geometry, we can can influence perovskite-polymer film flexibility, as well as perovskite crystal structure stability. Complementary Finite Element Analysis modeling will be used to map stress distributions, understand failure mechanisms, and rationalize the design of scaffold geometries for enhanced mechanical and functional performance. Synchrotron based Grazing Incidence Wide-Angle X-Ray Scattering will be used to determine the phase composition of the embedded perovskite in various geometries, and its evolution with temperature and humidity. Experimental findings will be combined with Density Functional Theory which will predict the energetics of phase transitions as a function of confinement geometry under environmental stressors.