Alloying and Defect Control within Chalcogenide Perovskites for Optimized Photovoltaic Application

Abstract

Through density functional theory calculations, we show that the alloy perovskite system BaZr1–x Ti x S3 (x < 0.25) is a promising candidate for producing high power conversion efficiency (PCE) solar cells with ultrathin absorber layers. To maximize the minority carrier lifetime, which is important for achieving high PCE, the defect calculations show that BaZr1–x Ti x S3 films should be synthesized under moderate (i.e., near stoichiometric) growth conditions to minimize the formation of deep-level defects. The perovskite BaZrS3 is also found to exhibit ambipolar self-doping properties, indicating the ability to form homo p–n junctions. However, our theoretical calculations and experimental solid-state reaction efforts indicate that the doped perovskite BaZr1–x Ti x S3 (x > 0) may not be stable under thermal equilibrium growth conditions. Calculations of decomposition energies suggest that introducing compressive strain may be a plausible approach to stabilize BaZr1–x Ti x S3 thin films.

Selection Metric for Photovoltaic Materials Screening Based on Detailed-Balance Analysis

“…This has frequently not been implemented correctly and has led to confusion and mistakes in the past [37][38][39][40][41][42][43][44][45][46][47][48][49]. The internal and external parameters used in the scope of this work are listed in Table I as well as the equations that connect an internal parameter with its external counterpart.…”

“…One of the first and maybe most prominent examples of such a selection metric proposed for computational materials screening is presented by Yu and Zunger in 2012 [37] and has been widely used to estimate efficiency limits in the last years [38][39][40][41][42][43][44][45][46][47][48][49]. In their paper, they proposed a "spectroscopic limited maximum efficiency" SLME selection metric that aims to calculate efficiency limits for non-step like absorption coefficients beyond the radiative limit.…”

Perovskite Solar Absorbers: Materials by Design

“…In addition, the alloy BaZr(O x S 1− x ) 3 was synthesized, and a widely tunable bandgap from 1.73 to 2.87 eV with varying S concentration was observed. Two other recent experiments have reported the bandgap of BaZrS 3 to be between 1.83 and 1.85 eV . This small discrepancy requires further experiments to resolve.…”

“…Meng et al studied the alloy and defect properties of BaZrS 3 based on DFT calculations . They investigated the alloy BaZrS 3 with Ti at the Zr sites and Se at the S sites.…”

Applications of ferroelectrics in photovoltaic devices

“…At the same time, the advantage of accurately reproducing the target component is lost, and the deposition rate is lower. A method in which different molecular beams or atomic beams are used for directly bombarding the substrate is called molecular beam epitaxy (MBE) [33]. MBE can be used to grow films with atomic scale thickness.…”