Advanced mechanisms, innovative designs, and optimized simulations of electron transport channels toward enhance performance in Sb2S3 solar cells

Abstract

Sb2S3 films are susceptible to the formation of nanogap defects during the crystallization process, leading to their experimental power conversion efficiency (PCE) falling significantly short of the theoretical limit. This investigation presents, a groundbreaking Sb2S3 photovoltaic device model that integrates perovskite within these nanogaps, and systematically examines the mechanisms for enhancing the PCE. Our findings reveal that incorporating perovskite within the nanogaps yields a 10% enhancement in optical absorption performance. Furthermore, perovskite nanogaps function as effective electron transport channels, significantly reducing the recombination of photogenerated carriers within the highly defective Sb2S3. The dimensions and arrangement of the nanochannels play a pivotal role in determining device performance, with optimal measurements of 5 nm in width and 15 nm in spacing. Additionally, this study examines the universality of the nanochannel structure. The projected PCE of this innovative structure is an impressive 25.40%. These findings provide valuable theoretical guidance for designing high-efficiency Sb2S3 solar cells.

1. Introduction

The growing global demand for renewable energy propels significant research into solar cells as an effective means for clean and sustainable power generation [1 −11]. Sb2S3 has emerged as a promising photovoltaic material, composed of earth-abundant and nontoxic elements [12]. It exhibits outstanding photoelectric properties, including a high absorption coefficient (α >10^4 cm^−1) [13], a suitable bandgap [14], and high electron (μn≈10 cm^2/(V·s)) [15] and hole (μp≈2.6 cm^2/(V·s)) mobilities [16]. As a binary compound with a single stable phase, Sb2S3 circumvents the detrimental formation of secondary phases. Its experimentally measured bandgap displays considerable variability (1.5−2.2 eV) depending on the preparation methods and conditions, which differs from theoretical predictions [14, 17 −19]. Theoretically, single-junction Sb2S3 solar cells may achieve power conversion efficiencies (PCEs) of 18.42% to 31.64% [20], and this material is also applicable in tandem structures [21]. These attributes endow Sb2S3 with considerable photovoltaic potential.

Nevertheless, the practical performance of Sb2S3 devices remains substantially below theoretical expectations, chiefly due to poor film crystallinity and high defect densities [22]. Considerable efforts have been directed towards solution-based processing to enhance film quality and approach the Shockley-Queisser (SQ) limit [18, 23 −28]. Techniques such as optimizing deposition (e.g., chemical bath [29], rapid thermal evaporation [30]), controlling crystal orientation on substrates like titanium dioxide (TiO2) [31], and utilizing quasi-epitaxial growth via buffer layers [11] have led to incremental increases in PCEs from 3.4% to 5.4%. While these methods have notably improved device efficiency by refining film quality and interface properties, a critical bottleneck limiting device performance persists. Specifically, nanoscale gap defects inherent in the crystalline domains of Sb2S3 severely hinder carrier transport and collection, thereby limiting further enhancement of the PCE.

Recently, ZHU et al [32] innovatively addressed the nanoscale gaps in Sb2S3 crystalline films by incorporating perovskite, resulting in a groundbreaking Sb2S3 solar cell structure. This novel design achieved a record PCE of 8.32%, demonstrating t