Exploring the effect of oxygen environment on the Mo/CdTe/CdSe solar cell substrate configuration

Yang, Xiaolei; Long, Yuchen; Zheng, Yi; Wang, Jiayi; Zhou, Biao; Xie, Shenghui; Li, Bing; Zhang, Jingquan; Hao, Xia; Karazhanov, Smagul; Zeng, Guanggen; Feng, Li

doi:10.1016/j.mssp.2022.107267

Cited by 2 publications

(1 citation statement)

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“…This results in a total of 82 unique defects across the seven mixed compositions, which are of interest in CdTe solar cells where Se is often mixed at the anion site. [54][55][56][57][58] DFEs are computed for each defect in 5 q states under Cd-rich and Te/Se-rich conditions to obtain the two extreme ranges of energies, and all the IS are collected from the optimization runs. Total datasets of a few hundred points are thus compiled, as shown in Table I.…”

Section: Datasetmentioning

confidence: 99%

Accelerating defect predictions in semiconductors using graph neural networks

Rahman,

Gollapalli,

Manganaris

et al. 2024

APL Machine Learning

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First-principles computations reliably predict the energetics of point defects in semiconductors but are constrained by the expense of using large supercells and advanced levels of theory. Machine learning models trained on computational data, especially ones that sufficiently encode defect coordination environments, can be used to accelerate defect predictions. Here, we develop a framework for the prediction and screening of native defects and functional impurities in a chemical space of group IV, III–V, and II–VI zinc blende semiconductors, powered by crystal Graph-based Neural Networks (GNNs) trained on high-throughput density functional theory (DFT) data. Using an innovative approach of sampling partially optimized defect configurations from DFT calculations, we generate one of the largest computational defect datasets to date, containing many types of vacancies, self-interstitials, anti-site substitutions, impurity interstitials and substitutions, as well as some defect complexes. We applied three types of established GNN techniques, namely crystal graph convolutional neural network, materials graph network, and Atomistic Line Graph Neural Network (ALIGNN), to rigorously train models for predicting defect formation energy (DFE) in multiple charge states and chemical potential conditions. We find that ALIGNN yields the best DFE predictions with root mean square errors around 0.3 eV, which represents a prediction accuracy of 98% given the range of values within the dataset, improving significantly on the state-of-the-art. We further show that GNN-based defective structure optimization can take us close to DFT-optimized geometries at a fraction of the cost of full DFT. The current models are based on the semi-local generalized gradient approximation-Perdew–Burke–Ernzerhof (PBE) functional but are highly promising because of the correlation of computed energetics and defect levels with higher levels of theory and experimental data, the accuracy and necessity of discovering novel metastable and low energy defect structures at the PBE level of theory before advanced methods could be applied, and the ability to train multi-fidelity models in the future with new data from non-local functionals. The DFT-GNN models enable prediction and screening across thousands of hypothetical defects based on both unoptimized and partially optimized defective structures, helping identify electronically active defects in technologically important semiconductors.

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