Xi Chen,Malin Li,Shi-Ping Wang,Chunzhong Wang,Zexiang Shen,Fu-Quan Bai,Fei Du
Selenium-based materials are considered as desirable candidates for potassium-ion and sodium-ion storage. Herein, an in situ fabrication method is developed to prepare an integrated cuprous selenide electrode by means of directly chemical selenization of the copper current collector with commercial selenium powder. Interestingly, only the electrolyte of 1 m potassium hexafluorophosphate dissolved in 1,2-dimethoxyethane with higher highest occupied molecular orbital energy and lower desolvation energy facilitates the formation of polyselenide intermediates and the further selenization of the copper current collector. Benefiting from the unique thin-film-like nanosheet morphology and the robust structural stability of the integrated electrode, the volume change and the loss of selenide species could be effectively restrained. Therefore, high performance is achieved in both potassium-ion batteries (462 mA h g −1 at 2 A g −1 for 300 cycles) and sodium-ion batteries (775 mA h g −1 at 2 A g −1 for 4000 cycles). The facile fabrication strategy paves a new direction for the design and preparation of high-performance electrodes.
Developing well-crystallized light-absorbing layers remains a formidable challenge in the progression of kesterite Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells. A critical aspect of optimizing CZTSSe lies in accurately governing the high-temperature selenization reaction. This process is intricate and demanding, with underlying mechanisms requiring further comprehension. This study introduces a precursor microstructure-guided hetero-nucleation regulation strategy for high-quality CZTSSe absorbers and well-performing solar cells. The alcoholysis of 2-methoxyethanol (MOE) and the generation of high gas-producing micelles by adding hydrogen chloride (HCl) as a proton additive into the precursor solution are successfully suppressed. This tailored modification of solution components reduces the emission of volatiles during baking, yielding a compact and dense precursor microstructure. The reduced-roughness surface nurtures the formation of larger CZTSSe nuclei, accelerating the ensuing Ostwald ripening process. Ultimately, CZTSSe absorbers with enhanced crystallinity and diminished defects are fabricated, attaining an impressive 14.01% active-area power conversion efficiency. The findings elucidate the influence of precursor microstructure on the selenization reaction process, paving a route for fabricating high-quality kesterite CZTSSe films and high-efficiency solar cells.
Antimony selenide (Sb 2 Se 3 ) is a potential absorber material for environment-friendly and cost-efficient photovoltaics and has achieved considerable progress in recent years. However, the severe open-circuit voltage ( V oc ) deficit ascribed to the interface and/or bulk defect states has become the main obstacle for further efficiency improvement. In this work, Sb 2 Se 3 absorber layer was prepared by an effective combination reaction involving sputtered and selenized Sb precursor thin films . The self-assembled growth of Sb 2 Se 3 thin films with large crystal grains, benign preferential orientation, and accurate chemical composition were successfully fulfilled under an appropriate thickness of Sb precursor and an optimized selenization scenario. Substrate structured Sb 2 Se 3 thin-film solar cells, a champion device with a power-conversion efficiency of 6.84%, were fabricated. This device is comparable to state-of-the-art ones and represents the highest efficiency of sputtered Sb 2 Se 3 solar cells. Importantly, the high V oc of 504 mV is closely related to the reduced deep level defect density for the Sb 2 Se 3 absorber layer, the passivated interfacial defects for Sb 2 Se 3 /CdS heterojunction interface, and the additional heterojunction heat treatment-induced Cd and S inter-diffusion. This significantly improved V oc demonstrates remarkable potential to broaden its scope of applications for Sb 2 Se 3 solar cells.
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