The electron transport layer(ETL) plays an important role in planar heterojunction perovskite solar cell(PSCs),by affecting the light-harvesting, electron injection and transportation processes, and especially the crystallization of perovskite absorber. In this work, we utilized a commercial TKD-TiO_2 nanoparticle with a small diameter of 6 nm for the first time to prepare a compact ETL by spin coating. The packing of small-size particles endowed TKD-TiO_2 ETL an appropriate surface-wettability, which is beneficial to the crystallization of perovskite deposited via solution-processed method. The uniform and high-transmittance TKD-TiO_2 films were successfully incorporated into PSCs as ETLs. Further careful optimization of ETL thickness gave birth to a highest power conversion efficiency of 11.0%, which was much higher than that of PSC using an ETL with the same thickness made by spray pyrolysis. This TKD-TiO_2 provided a universal solar material suitable for the further large-scale production of PSCs. The excellent morphology and the convenient preparation method of TKD-TiO_2 film gave it an extensive application in photovoltaic devices.
Peng ChenYinglin WangMeiqi WangXintong ZhangLingling WangYichun Liu
Wide bandgap(3.37 eV)and high excitonbinding energy of ZnO(60 meV)make it a promising candidate for ultraviolet light-emitting diodes(LEDs)and low-threshold lasing diodes(LDs).However,the difficulty in producing stable and reproducible high-quality p-type ZnO has hindered the development of ZnO p–n homojunction LEDs.An alternative strategy for achieving ZnO electroluminescence is to fabricate heterojunction devices by employing other available p-type materials(such as p-GaN)or building new device structures.In this article,we will briefly review the recent progress in ZnO LEDs/LDs based on p–n heterostructures and metal–insulatorsemiconductor heterostructures.Some methods to improve device efficiency are also introduced in detail,including the introduction of Ag localized surface plasmons and single-crystalline nanowires into ZnO LEDs/LDs.
Single-phased,high-color-rendering index(CRI)white-light phosphors are emerging as potential phosphor-converted white-light-emitting diodes(WLEDs)and as an alternative to blends of tricolor phosphors.However,it is a challenge to create a high CRI white light from a single-doped activator.Here,we present a high CRI(Ra 591)white-light phosphor,Sr_(5)(PO_(4))_(3-x)(BO_(3))_(x)Cl:Eu^(2+),composed of Sr5(PO4)3Cl as the beginning member and Sr_(5)(BO_(3))_(3)Cl as the end member.This work utilized the solid-solution method,and tunable Eu^(2+) emission was achieved.Color-tunable Eu^(2+) emissions in response to structural variation were observed in Sr_(5)(PO_(4))_(3-x)(BO_(3))_(x)Cl solid solutions.This was further confirmed using X-ray Rietveld refinement,electron paramagnetic resonance spectroscopy,and in the photoluminescence spectra.The color-tunable emissions included the white light that originated from the combination of the blue emission of Sr_(5)(PO_(4))_(3)Cl:Eu^(2+) and an induced Eu^(2+) yellow emission at approximately 550 nm in the solid solution.Importantly,the white-light phosphors showed a greater R9590.2 under excitation at 365 nm.This result has rarely been reported in the literature and is greater than that of(R9514.3)commercial Y_(3)A_(l5)O_(12):Ce^(3+)-based WLEDs.These findings demonstrate the great potential of Sr_(5)(PO_(4))_(3-x)(BO_(3))_(x)Cl:0.04Eu^(2+) as a white-light phosphor for near-UV phosphor-converted WLEDs.These results also provide a shortcut for developing a high CRI white-light phosphor from a single Eu^(2+)-doped compound.
Peng-Peng DaiCong LiXin-Tong ZhangJun XuXi ChenXiu-Li WangYan JiaXiaojun WangYi-Chun Liu
