Molecular exchange and passivation at interface afford high-performing perovskite solar cells with efficiency over 24%

The interface is crucial for perovskite solar cells(PSCs).However,voids at interfaces induced by the trapped hygroscopic dimethyl sulfoxide(DMSO)can reduce charge extraction and accelerate the film degradation,seriously damaging the efficiency and stability.In this work,4,4’-dinonyl-2,2’-dipyridine(DN-DP),a Lewis base with long alkyl chains is introduced to solve this problem.Theoretical calculated and experimental results confirm that the dipyridyl group on DN-DP can more strongly coordinate with Pb^(2+)than that of the S=O group on DMSO.The strong coordination effect plays a crucial role in removing the DMSO-based adduct and reducing the formation of voids.Due to the electron-donating properties of pyridine,the existence of DN-DP in the perovskite film can passivate the defects and optimize the energy level alignment of the perovskite configuration.The open-circuit voltage(VOC)of the DN-DP-based PSC is improved from 1.107 V(control device)to 1.153 V,giving rise to a power conversion efficiency(PCE)of24.02%.Furthermore,benefiting from the moisture resistance stemming from the hydrophobic nonyl group,the PCE retains 90.4%of the initial performance after 1000 h of storage in the ambient condition.

State-of-the-art advances in vacancy defect engineering of graphitic carbon nitride for solar water splitting

Developing low-cost,efficient,and stable photocatalysts is one of the most promising methods for large-scale solar water splitting.As a metal-free semiconductor material with suitable band gap,graphitic carbon nitride(g-C_(3)N_(4))has attracted attention in the field of photocatalysis,which is mainly attributed to its fascinating physicochemical and photoelectronic properties.However,several inherent limitations and shortcomings—involving high recombination rate of photocarriers,insufficient reaction kinetics,and optical absorption—impede the practical applicability of g-C_(3)N_(4).As an effective strategy,vacancy defect engineering has been widely used for breaking through the current limitations,considering its ability to optimize the electronic structure and surface morphology of g-C_(3)N_(4) to obtain the desired photocatalytic activity.This review summarizes the recent progress of vacancy defect engineered g-C_(3)N_(4) for solar water splitting.The fundamentals of solar water splitting with g-C_(3)N_(4) are discussed first.We then focus on the fabrication strategies and effect of vacancy generated in g-C_(3)N_(4).The advances of vacancy-modified g-C_(3)N_(4) photocatalysts toward solar water splitting are discussed next.Finally,the current challenges and future opportunities of vacancy-modified g-C_(3)N_(4) are summarized.This review aims to provide a theoretical basis and guidance for future research on the design and development of highly efficient defective g-C_(3)N_(4).

Localized Electrons Accelerated Ionic and Charge Transfer for Superior Lithium Storage

The electrochemical energy storage performance is greatly determined by the charge transfer and ion transportation occurring in the electrode materials.Therefore,the enhancement of electric conductivity and ionic mobility is vital for high-performing and stable metal ion batteries.Here,we report the properties of oxygen vacancies(VO)and carbon co-doped TiO_(2) hollow spheres(HS-TiO_(2))and compared them with fully oxidized white TiO_(2) hollow spheres(W-TiO_(2)).Theoretical calculations and experimental results revealed that the introduction of carbon dopant and VO in anatase TiO_(2) reduced the bandgap and the existence of localized electrons,leading to a lower migration barrier of Li ions that promoted faster ion diffusion kinetics,enabling the HS-TiO_(2) with higher reversibility during the insertion and extraction of Li ions than the W-TiO_(2).This HS-TiO_(2) delivered superior lithium storage properties with a specific discharge capacity of 214.6 mAh g^(-1) for the 100th cycle at 200 mA g^(-1) and 116.3 mAh g^(-1) over 2000 cycles at a high rate of 2 A g^(-1).

Nitrogen doping induced by intrinsic defects of recycled polyethylene terephthalate-derived carbon nanotubes

The indiscriminate utilization of nondegradable polyethylene terephthalate(PET)-based products has triggered serious environmental pollution that has to be resolved vigorously.A simple synthesis of N-doped carbon nanotubes from recycled PET(NCNTs_(r-PET))was developed by a nitric acid-assisted hydrothermal method.Experimental results and theoretical calculations show that the intrinsic defects in CNTs_(r-PET)would induce N-doping by NH_(3)generated from nitric acid during the hydrothermal process,thus producing the NCNTs_(r-PET).The life cycle assessment proves that the developed method for N-doped CNTs using r-PET as the carbon source is more environmentally friendly than the conventional chemical vapor deposition using acetylene as the carbon source.As a typical application,the NCNTs_(r-PET)delivered an impressive sodium storage capacity with an ultralong lifespan.This work not only provides a new route to upcycling waste plastics into valuable carbonaceous materials in an ecofriendly manner,but also reveals a basic understanding of the N-doping mechanism in carbonaceous materials.