Towards operation-stabilizing perovskite solar cells:Fundamental materials,device designs,and commercial applications

Over the last decade,perovskite solar cells(PSCs)have drawn extensive atten-tion owing to their high power conversion efficiency(single junction:26.1%,perovskite/silicon tandem:33.9%)and low fabrication cost.However,the short lifespan of PSCs with initial efficiency still blocks their practical applications.This operational instability may originate from the intrinsic and extrinsic deg-radation of materials or devices.Although the lifetime of PSCs has been prolonged through component,crystal,defect,interface,encapsulation engineering,and so on,the systematic analysis of failure regularity for PSCs from the perspective of materials and devices against multiple operating stressors is indispensable.In this review,we start with elaboration of the predominant degradation pathways and mechanism for PSCs under working stressors.Then the strategies for improving long-term durability with respect to fundamental materials,interface designs,and device encapsulation have been summarized.Meanwhile,the key results have been discussed to understand the limitation of assessing PSCs stability,and the potential applications in indoor photovoltaics and wearable electronics are demonstrated.Finally,promising proposals,encompassing material processing,film formation,interface strengthening,structure designing,and device encapsulation,are provided to improve the operational stability of PSCs and promote their commercialization.

Insight into modified biochars and their immobilizing effects on heavy metal(loid)s in contaminated soils: Mechanisms and influencing factors

Soil contamination by heavy metal(loid)s is a considerable environmental concern,and immobilization is a promising way to reduce toxicity.In recent years,modified/engineered biochars have gained enormous attention for their use in soil remediation,and various studies have reported notable results from their application and their ability to immobilize heavy metal(loid)s.In this review,a summary of publications on the utilization of modified biochars is presented to address the heavy metal(loid)threat in soils.Various modified/engineered biochars were described from the review of relevant publications.Modification causes great changes in biochar surface chemistry,such as increases in pore volume,surface functional groups,and metal binding sites,which can be observed through various analytical techniques,including Brunauer-Emmett-Teller,X-ray photoelectron spectroscopy,X-ray diffraction,Fourier transform infrared spectroscopy,and magnetism.Such analytical approaches elucidate immobilization mechanisms of adsorption,precipitation,surface complexation,and cation exchange between biochar and metal(loid)ions.In addition,the performance of biochar in remediating heavy metal(loid)s also leads to considerable improvements in soil conditions.Additionally,many factors that influence metal(loid)immobilization by biochar in soil,such as pH,redox potential,microorganisms,and climate regime,are highlighted.Finally,this paper emphasizes that using modified biochars as an immobilizing agent for remediation of heavy metal(loid)-polluted soils is promising and would be practicable if a comprehensive mechanism of their long-term stability in soil is well elucidated.