Fabrication of highly luminescent TiO_(2):Eu^(3+) thin film with low annealing temperature requirement by co-doping with Sn^(4+) ions

Rare earth(RE)-doped TiO_(2)thin films possess important applications in modern optoelectronic devices.However,the high annealing temperature requirement remains a critical restriction in device fabrications.In this work,TiO_(2)thin films doped with trivalent europium(Eu^(3+))ions were fabricated by a convenient sol-gel approach and subsequent annealing treatment.Interestingly,it is found that the optimal post-annealing temperature of TiO_(2):Eu^(3+)thin film is dramatically reduced from 800 to 300℃by incorporating 10 at%Sn^(4+)into the sol precursor.The Sn-incorporated film annealed at 300℃shows a 4-fold enhancement in photoluminescence(PL)intensity related to Eu^(3+)ions to the optimized Sn-free film.Systematic analysis reveals that this enhancement is attributed to Sn element promoting the crystallization of both anatase TiO_(2)and rutile SnO_(2)clusters at 300℃,which provides sufficient SnO_(2)/TiO_(2)crystal boundary facilitating Eu^(3+)to occupy and sensitized by SnO_(2)crystals.These results provide valuable insights into fabricating highly luminescent RE-doped TiO_(2)thin films with low annealing temperature requirement,which is essential for designing optoelectronic devices based on RE materials more freely in the future.

Recent advances on interface engineering of perovskite solar cells

Lead halide perovskite solar cells(PSCs)have been rapidly developed in the past decade.Owing to its excellent power conversion efficiency with robust and low-cost fabrication,perovskite quickly becomes one of the most promising candidates for the next-generation photovoltaic technology.With the development of PSCs,the interface engineering has witnessed its increasingly critical role in maximizing the device performance as well as the long-term stability,because the interfaces in PSCs are closely correlated with the defect management,carrier dynamics and surface passivation.This review focuses on interfacial modification between the perovskite active layer and the charge transport layer,as well as the recent advances on high-efficiency and stable PSCs driven by interface engineering strategies.The contributing roles of interface engineering in terms of defect passivation,inhibiting ion migration,optimization of energy band alignment and morphological control are discussed.Finally,based on the latest progress and advances,strategies and opportunities for the future research on interface engineering for PSCs are proposed to promote the development of perovskite photovoltaic technology.

Unresolved Excess Accumulation of Myelin-Derived Cholesterol Contributes to Scar Formation after Spinal Cord Injury

Spinal cord injury triggers complex pathological cascades,resulting in destructive tissue damage and incomplete tissue repair.Scar formation is generally considered a barrier for regeneration in the central nervous system.However,the intrinsic mechanism of scar formation after spinal cord injury has not been fully elucidated.Here,we report that excess cholesterol accumulates in phagocytes and is inefficiently removed from spinal cord lesions in young adult mice.Interestingly,we observed that excessive cholesterol also accumulates in injured peripheral nerves but is subsequently removed by reverse cholesteroltransport.Meanwhile,preventing reverse cholesterol transport leads to macrophage accumulation and fibrosis in injured peripheral nerves.Furthermore,the neonatal mouse spinal cord lesions are devoid of myelin-derived lipids and can heal without excess cholesterol accumulation.We found that transplantation of myelin into neonatal lesions disrupts healing with excessive cholesterol accumulation,persistent macrophage activation,and fibrosis.Myelin internalization suppresses macrophage apoptosis mediated by CD5L expression,indicating that myelin-derived cholesterol plays a critical role in impaired wound healing.Taken together,our data suggest that the central nervous system lacks an efficient approach for cholesterol clearance,resulting in excessive accumulation of myelin-derived cholesterol,thereby inducing scar formation after injury.