Ideal Bandgap in a 2D Ruddlesden-Popper Perovskite Chalcogenide for Single-junction Solar Cells

TL;DR

This study reports the growth and optical characterization of high-quality 2D Ruddlesden-Popper perovskite chalcogenide crystals, demonstrating their potential for efficient single-junction solar cells due to favorable luminescent properties.

Contribution

It presents the first synthesis of high-quality single crystals of Ba3Zr2S7 2D perovskite chalcogenide and evaluates their optical properties relevant for photovoltaics.

Findings

Bright photoluminescence at 1.28 eV

External luminescence efficiency up to 0.15%

Recombination time of ~65 ns

Abstract

Transition metal perovskite chalcogenides (TMPCs) are explored as stable, environmentally friendly semiconductors for solar energy conversion. They can be viewed as the inorganic alternatives to hybrid halide perovskites, and chalcogenide counterparts of perovskite oxides with desirable optoelectronic properties in the visible and infrared part of the electromagnetic spectrum. Past theoretical studies have predicted large absorption coefficient, desirable defect characteristics, and bulk photovoltaic effect in TMPCs. Despite recent progresses in polycrystalline synthesis and measurements of their optical properties, it is necessary to grow these materials in high crystalline quality to develop a fundamental understanding of their optical properties and evaluate their suitability for photovoltaic application. Here, we report the growth of single crystals of a two-dimensional (2D) perovskite chalcogenide, Ba3Zr2S7, with a natural superlattice-like structure of alternating double-layer perovskite blocks and single-layer rock salt structure. The material demonstrated a bright photoluminescence peak at 1.28 eV with a large external luminescence efficiency of up to 0.15%. We performed time-resolved photoluminescence spectroscopy on these crystals and obtained an effective recombination time of ~65 ns. These results clearly show that 2D Ruddlesden-Popper phases of perovskite chalcogenides are promising materials to achieve single-junction solar cells.