Halogen-free guanidinium-based perovskite solar cell with enhanced stability

Yang

ACS Appl. Mater. Interfaces

et al. 2021

The hole density of individual copper sulfide nanocrystals (Cu2–x S NCs) is determined from the stoichiometric mismatch (x) between copper and sulfide atoms. Consequently, the electronic properties of the material vary over a range of x. To exploit Cu2–x S NCs in devices, assemblies of NCs are typically required. Herein, we investigate the influence of x, referred to as the stoichiometric doping effect, on the structural, optical, electrical, and thermoelectric properties of electronically coupled Cu2–x S NC assemblies. The doping process is done by immersing the solid NC assemblies into a solution containing a Cu(I) complex for different durations (0–10 min). As Cu+ gradually occupied the copper-deficient sites of Cu2–x S NCs, x could be controlled from 0.9 to less than 0.1. Consequently, the near-infrared (NIR) absorbance of Cu2–x S NC assemblies changes systematically with x. With increasing x, electrical conductivity increased and the Seebeck coefficient decreased systematically, leading to the maximal thermoelectric power factor from a film of Cu2–x S NCs at an optimal doping condition yielding x = 0.1. The physical characteristics of the Cu2–x S NC assemblies investigated herein will provide guidelines for exploiting this emerging class of nanocrystal system based on doping.

Section: ■ Results and Discussionmentioning

confidence: 95%

Stoichiometric Doping of Highly Coupled Cu_2–xS Nanocrystal Assemblies

Yang

ACS Appl. Mater. Interfaces

et al. 2021

“…The Gua + can incorporate into the PVK structure and become one of the organic cations in the PVK crystals, so that it can participate in the formation of low‐dimensional PVK when mixes with Pb(BrI) 2 . [ 25–27 ] The O and N atoms of SM − containing lone electron pairs can coordinate with Pb 2+ . Dual‐function of GuaSM drives simultaneously, the defects and recombination are effectively reduced.…”

Section: Introductionmentioning

confidence: 99%

Additive Engineering by Bifunctional Guanidine Sulfamate for Highly Efficient and Stable Perovskites Solar Cells

Liu

Yang

et al. 2020

Small

High efficiency and good stability are the challenges for perovskite solar cells (PSCs) toward commercialization. However, the intrinsic high defect density and internal nonradiative recombination of perovskite (PVK) limit its development. In this work, a facile additive strategy is devised by introducing bifunctional guanidine sulfamate (GuaSM; CH6N3+, Gua+; H2N−SO3−, SM−) into PVK. The size of Gua+ ion is suitable with Pb(BrI)2 cavity relatively, so it can participate in the formation of low‐dimensional PVK when mixed with Pb(BrI)2. The O and N atoms of SM− can coordinate with Pb2+. The synergistic effect of the anions and cations effectively reduces the trap density and the recombination in PVK, so that it can improve the efficiency and stability of PSCs. At an optimal concentration of GuaSM (2 mol%), the PSC presents a champion power conversion efficiency of 21.66% and a remarkably improved stability and hysteresis. The results provide a novel strategy for highly efficient and stable PSCs by bifunctional additive.

“…Meanwhile, the S 2p spectra of FeCoNiS x /NF and NiCoS x /NF are shown in Figure 3c. For NiCoS x /NF, the peaks located at the binding energy of 161.2 and 162.4 eV can be ascribed to the S 2p 3/2 and S 2p 1/2 , while the peak of 168.2 eV corresponds to S−O species [38] . In a contrast, the FeCoNiS x /NF also shows similar typical peaks, except for the slight peak shifts.…”

Section: Resultsmentioning

confidence: 87%

Hierarchical Metal Sulfides Heterostructure as Superior Bifunctional Electrode for Overall Water Splitting

Feng

Tong

2022

ChemSusChem

The development of highly active bifunctional electrocatalysts for overall water splitting is of significant importance, but huge challenges remain. The key element depends on engineering the electronic structure and surface properties of material to achieve improved catalytic activity. Herein, a hierarchical nanowire array of metal sulfides heterostructure on nickel foam (FeCoNiSx/NF) was designed as a novel type of hybrid electrocatalyst for overall water splitting. The hybrid structure endowed plenty of catalytic active sites, strong electronic interactions, and high interfacial charge transferability, leading to superior bifunctional performance. As a result, the FeCoNiSx/NF catalyst delivered low overpotentials of 97 and 260 mV at the current density of 50 mA cm−2 for hydrogen and oxygen evolution reactions, respectively. Moreover, the FeCoNiSx/NF‐based water electrolyzer exhibited a small potential of 1.57 V for a high current density of 50 mA cm−2. These results indicate the promising application potential of FeCoNiSx/NF electrode for hydrogen generation. This work provides a new approach to develop robust hybrid materials as the highly active electrode for electrocatalytic water splitting.