从Cu2ZnSnS4到Cu2CdGe（S，Se）4优化硅藻土太阳能电池,Journal of Materials Chemistry A

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从Cu2ZnSnS4到Cu2CdGe（S，Se）4优化硅藻土太阳能电池
Journal of Materials Chemistry A ( IF 10.7 ) Pub Date : 2021-4-1 , DOI: 10.1039/d0ta11603c
Robert B. Wexler _{1,

2,

3,

4} , Gopalakrishnan Sai Gautam _{1,

2,

3,

4} , Emily A. Carter _{1,

2,

3,

4,

5}

Affiliation

基于原型吸收体材料Cu ₂ ZnSnS ₄（CZTS）的Kesterite太阳能电池便宜，无毒且化学稳定，因此使其成为有前途的超越Si的光伏技术。然而，它们的效率受到缺陷的形成的限制，这些缺陷会通过形成深陷阱来减少短路电流，该陷阱会通过Shockley-Read-Hall机制发生光激发电荷载流子的非辐射重组。为了抑制这些缺陷的形成，特别是最有害的2Cu _Zn + Sn _Zn反位簇，我们设计了一种离子取代策略，该方法涉及完全Cd和Ge取代以及部分硒化，最终达到最佳组成Cu₂ CdGeS₃ Se（CCdGSSe）。使用密度泛函理论和从头算热力学，我们预测完全的_Cd和Ge取代将导致深陷阱诱导2Cu_Cd + Ge_Cd的形成能增加125％。此外，相对于Shockley-Queisser极限，25％的硒化可优化预测的带隙（1.43–1.47 eV，由混合功能计算得出）。除了提供一种实用且新颖的离子取代策略外，我们还阐明了Ge和Se抑制和促进缺陷的机理，并分别强调了惰性对效应和金属-硫族元素键价的关键作用。由于其理想的热力学和电子特性，CCdGSSe应重新激发对基于硅藻土的太阳能电池的研究，优化由离子取代和二元后组成提供的丰富材料空间。

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Optimizing kesterite solar cells from Cu2ZnSnS4 to Cu2CdGe(S,Se)4

Kesterite solar cells, based on the prototypical absorber material Cu₂ZnSnS₄ (CZTS), are cheap, nontoxic, and chemically stable, thus rendering them promising, beyond-Si photovoltaic technologies. Their efficiencies, however, are limited by the formation of defects that decrease the short-circuit current by creating deep traps where nonradiative recombination of photoexcited charge carriers occurs via the Shockley–Read–Hall mechanism. To suppress the formation of these defects, specifically the most deleterious 2Cu_Zn + Sn_Zn antisite cluster, we devised an ion substitution strategy involving complete Cd- and Ge-substitution and partial selenization, ultimately arriving at the optimal composition, Cu₂CdGeS₃Se (CCdGSSe). Using density functional theory and ab initio thermodynamics, we predict that complete Cd- and Ge-substitution leads to a 125% increase in the formation energy of the deep-trap-inducing 2Cu_Cd + Ge_Cd. Additionally, 25% selenization optimizes the predicted band gap (1.43–1.47 eV, as calculated from a hybrid functional) with respect to the Shockley–Queisser limit. In addition to providing a practical and novel ion substitution strategy, we also elucidate the mechanisms of defect suppression and promotion by Ge and Se, highlighting the key role of the inert pair effect and metal-chalcogen bond covalency, respectively. Due to its ideal thermodynamic and electronic characteristics, CCdGSSe should reinvigorate research on kesterite-based solar cells, optimizing the rich materials space afforded by ion substitution and post-quinary compositions.

更新日期：2021-04-09

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