Wide-bandgap perovskites for efficient, stable tandems
Abstract
Organolead halide perovskites and their corresponding solar cells have reached impressive certified power conversion efficiencies (PCE) of 25.2% using < 1.55 eV-bandgap perovskites in single-junction cells. However, the PCE upper bound of single-junction device is limited by detailed balance theory (~33%). Tandem solar cells consisting of multiple absorber layers with different bandgaps offer to reduce thermalization losses and can thus surpass PCE of singlejunction cells. For efficient tandem architectures, the bandgaps of the subcells need to be appropriately matched. To take the advantage of the market-established silicon photovoltaics (PV), it is now important to develop novel approaches to translate these insights into wide-bandgap perovskites, which are required to achieve optimal performance in perovskite:c-Si tandem solar cells. Here we propose to undertake a combination of experimental and theoretical studies to gain an increased understanding of instability and Voc losses in wide-bandgap perovskites in solar cells. We will control perovskite thin film growth by using epitaxial anchoring, forming 2D/3D perovskite heterostructures, A-site cation selection, strain engineering, and low-Br concepts. We will exploit computational modelling studies as well as advanced material characterization such as in situ GIWAXS/GISAXS and neutron scattering. We will apply the resultant knowledge to predict, and then experimentally fabricate, new, efficient, and stable wide-bandgap perovskites for tandems. Our studies will provide a path to close the performance gap between 1.50 eV and 1.66-1.74 eVbandgap solar cells, enabling us to propose new strategies for the synthesis of ultra-stable widebandgap perovskites for perovskite:c-Si tandem applications. This project will have three themes. In the first, we will explore the compositional space of widebandgap perovskites. We will pursue this approach using a single-crystal materials science platform. In the second, we will explain phase segregation mechanisms in polycrystalline perovskite thin films. This knowledge will guide the development of strategies to prevent perovskite degradation and thus enable pathways to stable perovskite thin films exhibiting low defect densities. In the third, we will integrate the new materials developed in the theme 1 and 2 into solar cell platforms. We will transfer the learnings from 1.50-1.60 eV regime to 1.66 -1.74 eV and above, contributing to closing the efficiency-stability gap in wide-bandgap perovskite solar cells.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 20, 2020
- Source ID
- N000142012572
Entities
People
- Edward H. Sargent
Organizations
- Office of Naval Research
- United States Navy
- University of Toronto