Nanoscale Phovoltaics Laboratory On a Tip

Introduction

Next generation solar cells based on metal halide perovskite (MHP) materials promise cheaper and more energy-efficient photovoltaic and optoelectronic devices compared to current silicon-based technologies. To further advance MHP technology, however, will require fundamental understanding of processes leading to energy losses, unstable operation conditions, and premature aging.

Macroscopic Properties

The macroscopic properties of optoelectronic MHP devices are the result of the complicated interplay between structure and function. Thus, the key to understanding MHP materials is to look at the many nano- and microscale structures, including:

• Sub-granular twin domains
• Grain boundaries and interfaces
• Lateral variations in crystal orientations and facets

Project Aim

The aim of this project is to reveal fundamental nanoscale processes and explore the connections to the macroscopic properties of MHP materials.

Development of NanoPLOT

To achieve this, we will develop NanoPLOT, an innovative microscopy platform that combines:

1. The lateral resolution of state-of-the-art atomic force microscopy (AFM)
2. The high temporal and spectral resolution of ultrafast optical spectroscopy

Capabilities of NanoPLOT

NanoPLOT will not only allow spatially correlated mapping of:

• Local electron dynamics
• Photoemission spectra
• Nanoscale surface photovoltage
• Photocurrent or ion dynamics

The most exciting possibilities will come from entirely new imaging methods based on combinations of the available scanning probe and optical methods.

Experimental Techniques

Using the 2-10 nm wide AFM tip, we will address and excite individual nanostructures, enabling the characterization of optoelectronic properties at unprecedented spatial and temporal resolution.

Addressing Key Challenges

The new experimental capabilities will enable addressing some key challenges of MHP research, such as:

• Phase segregation and degradation effects
• Interface heterogeneity
• Strain effects

This will facilitate a deeper understanding of loss mechanisms and intrinsic instabilities that will enable more efficient and stable MHP solar cells.