Recent advances in Pb-Sn mixed perovskite solar cells

Organic-inorganic hybrid lead-tin perovskite solar cells(Pb-Sn PSCs)have attracted much attention because of their advantages of low toxicity,variable bandgap,and feasibility for all-perovskite tandem solar cells,and the current power conversion efficiency(PCE)has exceeded 23%.However,due to the rambunctious crystallization process,easily oxidized Sn(Ⅱ)and inadequate energy level arrangement,there are many defects in perovskite films resulting in serious carrier recombination,which makes PCE still lag Pb-based PSCs.The quality of perovskite films is an important factor affecting the overall device performance.The selection and optimization of transport layers not only determines the interface energy level arrangement but also affects the carrier transport.In this paper,the research progress in improving performance of Pb-Sn PSCs in recent years is reviewed from aspects of perovskite layer and transport layers.The profound understanding of different promotion methods is summarized as well.These results have certain guiding significance for the future development and commercial application of Pb-Sn PSCs.

Overcoming Perovskite Corrosion and De-Doping Through Chemical Binding of Halogen Bonds Toward Efficient and Stable Perovskite Solar Cells

4-tert-butylpyridine(TBP)is an indispensable additive for the hole transport layer in highly efficient perovskite solar cells(PSCs),while it can induce corrosion decomposition of perovskites and de-doping effect of spiro-OMeTAD,which present huge challenge for the stability of PSCs.Herein,halogen bonds provided by 1,4-diiodotetrafluorobenzene(1,4-DITFB)are employed to bond with TBP,simultaneously preventing perovskite decomposition and eliminating de-doping effect of oxidized spiro-OMeTAD.Various characterizations have proved strong chemical interaction forms between 1,4-DITFB and TBP.With the incorporation of halogen bonds,perovskite film can maintain initial morphology,crystal structure,and light absorbance;meanwhile,the spiro-OMeTAD film shows a relatively stable conductivity with good charge transport property.Accordingly,the device with TBP complex exhibits significantly enhanced stability in N_(2) atmosphere or humidity environment.Furthermore,a champion power conversion efficiency of 23.03%is obtained since perovskite is no longer damaged by TBP during device preparation.This strategy overcomes the shortcomings of TBP in n-i-p PSCs community and enhances the application potential of spiro-OMeTAD in fabricating efficient and stable PSCs.

Expert consensus on prevention and cardiopulmonary resuscitation for cardiac arrest in COVID-19

Background:Cardiopulmonary resuscitation(CPR)strategies in COVID-19 patients differ from those in patients suffering from cardiogenic cardiac arrest.During CPR,both healthcare and non-healthcare workers who provide resuscitation are at risk of infection.The Working Group for Expert Consensus on Prevention and Cardiopulmonary Resuscitation for Cardiac Arrest in COVID-19 has developed this Chinese Expert Consensus to guide clinical practice of CPR in COVID-19 patients.Main recommendations:1)A medical team should be assigned to evaluate severe and critical COVID-19 for early monitoring of cardiac-arrest warning signs.2)Psychological counseling and treatment are highly recommended,since sympathetic and vagal abnormalities induced by psychological stress from the COVID-19 pandemic can induce cardiac arrest.3)Healthcare workers should wear personal protective equipment(PPE).4)Mouth-to-mouth ventilation should be avoided on patients suspected of having or diagnosed with COVID-19.5)Hands-only chest compression and mechanical chest compression are recommended.6)Tracheal-intubation procedures should be optimized and tracheal-intubation strategies should be implemented early.7)CPR should be provided for 20-30 min.8)Various factors should be taken into consideration such as the interests of patients and family members,ethics,transmission risks,and laws and regulations governing infectious disease control.Changes in management:The following changes or modifications to CPR strategy in COVID-19 patients are proposed:1)Healthcare workers should wear PPE.2)Hands-only chest compression and mechanical chest compression can be implemented to reduce or avoid the spread of viruses by aerosols.3)Both the benefits to patients and the risk of infection should be considered.4)Hhealthcare workers should be fully aware of and trained in CPR strategies and procedures specifically for patients with COVID-19.

Recent process of plasma effect in organic solar cells

Due to the compromise between exciton diffusion length and light absorption, the active layer thickness of organic solar cells(OSCs) is limited. As we all know, embedding metal nanostructures into OSCs can improve the performance of OSCs by triggering surface plasma resonance, scattering, and other effect without increasing the physical thickness of light trapping layer. Besides, the plasma response and other roles will distinguish when metal nanostructures are embedded into different position of OSCs, which are equally important to the performance of OSCs. In this paper, the enhancement mechanisms of various metal nanostructures in different layers of OSCs are summarized from the electricity and optics aspects.This review also further highlights the progress of plasma effect and their working mechanism in OSCs,and it is expected to provide more perspective of plasma effect for performance enhancement of OSCs.

Improving the performance of perovskite solar cells by surface passivation

NiO has a perfect-aligned energy level with CH3 NH3 Pb I3 perovskite such that it serves as a hole transport layer(HTL),but Ni O-based perovskite solar cells(PSCs)still suffer from low efficiency due to the poor interface contact between the perovskite layer and the Ni O HTL,and haphazardly stacked perovskite grains.Herein,poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(1,4-benzo-{2,1,3}-thiadiazole)](PFBT)is introduced between the Ni O and perovskite layers in the form of a polymer aggregate to enhance perovskite crystallinity and decrease the interface charge recombination between perovskite and Ni O in PSCs,resulting in an improved performance.Moreover,PFBT modified perovskite films showed sharper,smoother,and more compact crystalline grains with fewer grain boundaries,leading to the decreased nonradiative recombination.This study offers a simple strategy to achieve highly efficient PSCs with the incorporation of polymer semiconductor aggregates to passivate the interface between the perovskite and Ni O layers.

Physical,mechanical and thermal properties of vacuum sintered HUST-1 lunar regolith simulant

Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years.Sintered lunar regolith is one of the most potential building materials for lunar bases.The physical,mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues.In this study,the HUST-1 lunar regolith simulant(HLRS)was sintered at 1030,1040,1050,1060,1070,and 1080℃.The effect of sintering temperature on the compressive strength was investigated,and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060℃.Then,the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized.It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080℃.Besides,the heat capacity,thermal conductivity,and coefficient of thermal expansion(CTE)of vacuum sintered HLRS at different temperatures were investigated.Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from-75 to 145℃.Besides,the thermal conductivity of the sintered sample is proportional to density.Finally,the two temperatures of 1040 and 1050℃were selected for a more detailed study of mechanical properties.The results showed that compressive strength of sintered sample is much higher than tensile strength.This study reveals the effects of sintering temperature on the physical,mechanical and thermal properties of vacuum sintered HLRS,and these material parameters will provide support for the construction of future lunar bases.