Interfacial modification using the cross-linkable tannic acid for highly-efficient perovskite solar cells with excellent stability

Although the performance of perovskite solar cells(PSCs)has been dramatically increased in recent years,stability is still the main obstacle preventing the PSCs from being commercial.PSC device instability can be caused by a variety of reasons,including ions diffusion,surface and grain boundary defects,etc.In this work,the cross-linkable tannic acid(TA)is introduced to modify perovskite film through post-treatment method.The numerous organic functional groups(–OH and C=O)in TA can interact with the uncoordinated Pb^(2+)and I^(-)ions in perovskite,thus passivating defects and inhibiting ions diffusion.In addition,the formed TA network can absorb a small amount of the residual moisture inside the device to protect the perovskite layer.Furthermore,TA modification regulates the energy level of perovskite,and reduces interfacial charge recombination.Ultimately,following TA treatment,the device efficiency is increased significantly from 21.31%to 23.11%,with a decreased hysteresis effect.Notably,the treated device shows excellent air,thermal,and operational stability.In light of this,the readily available,inexpensive TA has the potential to operate as a multipurpose interfacial modifier to increase device efficiency while also enhancing device stability.

三种常用临床指标在重症肺炎患者液体管理监测中的比较研究

目的探讨重症超声(CCUS)在ICU重症肺炎患者液体管理中的临床应用价值。方法选取2017年7月至2020年2月入住江苏大学附属人民医院ICU的99例重症肺炎患者,根据指导液体管理的方法不同,将所有患者分为中心静脉压(CVP)组(32例)、脉搏指示连续心排出量(PICCO)组(31例)和CCUS组(36例)。CVP组根据CVP及常规血流动力学指标(心率、平均动脉压等)指导液体管理;PICCO组应用PICCO指导液体管理;CCUS组应用CCUS动态监测患者心、肺及下腔静脉指标指导液体管理。通过比较3组肺功能(氧合指数、相关呼吸力学参数、机械通气时间)的指标差异,以及液体正平衡量和相关预后参数的差异,评估CCUS在指导重症肺炎患者液体管理方面是否具有一定的优势。结果3组患者治疗后第1、3、5、7天液体正平衡量、氧合指数、肺静态顺应性(C_(lst))、气道平台压(P_(plat))、呼气末正压(PEEP)比较,差异均有统计学意义(F=8.035、22.514、41.080、67.002、6.677,P均<0.05)。进一步两两比较发现,PICCO组和CCUS组治疗后第5、7天氧合指数、Clst均高于CVP组;治疗后第5、7天Pplat及治疗后第7天液体正平衡量和PEEP均低于CVP组同时间点(P均<0.05)。3组患者机械通气时间、肺水肿发生率及肺外器官损伤率比较,差异均有统计学意义(H=13.281,χ^(2)=8.949、8.655;P=0.001、0.007、0.013)。且CCUS组机械通气时间(P<0.05)、肺外器官损伤率(P<0.017)以及PICCO组和CCUS组肺水肿发生率(P均<0.017)均显著低于CVP组。结论CCUS能够很好地评估重症肺炎患者容量状态及其反应性,有助于制定有效的液体管理办法,及时改善肺部氧合,利于肺功能的恢复,缩短机械通气时间。

Low-cost dopant-free fluoranthene-based branched hole transporting materials for efficient and stable n-i-p perovskite solar cells

It has been widely recognized that hole transporting materials(HTMs)play a key role in the rapid progress of perovskite solar cells(PVSCs).However,common organic HTMs such as spiro-OMe TAD not only suffer from high synthetic costs,but also usually require the additional chemical doping process to improve their hole transport ability,which unfortunately induces the terrible stability issue.Therefore,it is urgent to develop low-cost dopant-free HTMs for efficient and stable PVSCs.In this work,we have successfully developed a new class of efficient dopant-free fluoranthene-based HTMs(TPF1–5)with quite low lab synthetic costs by combining donor-acceptor and branched structure designs.The detailed structure-property study revealed that tuning the twisted arms at different substitution sites would regulate the intermolecular interactions and film-forming ability,thereby significantly affecting the performance of the HTMs.By applying these HTMs in conventional PVSCs,the dopant-free TPF1-based devices not only achieved the best efficiency of 21.76%,which is comparable to that of the doped spiro-OMeTAD control devices,but also showed much better operational stability,which maintained over 87%of the initial efficiency under maximum power point tracking after 1038 h.

Hole-Transporting Materials with Rational Combination of Pyridine and Dibenzo[a,c]phenazine as Electron Acceptor for Dopant-Free Perovskite Solar Cells

Perovskite solar cells(PSCs)have been proven to be a promising option for photovoltaic conversion.With the aim to achieve efficient and stable PSCs,it is essential to explore dopant-free hole-transporting materials(HTMs)with high hole mobility.Herein,HTMs bearing electron donor(D)-electron acceptor(A)-electron donor(D)structures have been constructed with strong intramolecular charge transfer(ICT)effect,based on rational combination of dibenzo[a,c]phenazine and pyridine as electronic acceptors and anchoring groups to perovskite layer.Accordingly,high hole mobility(7.31×10^(-5) cm^(2)·V^(-1)·s^(-1))and photoelectric conversion efficiency(20.45%)have been achieved by dopant-free DPyP-based PSC.It afforded an efficient way to design HTMs with high hole mobility by adjustment of molecular configurations and electronic property of conjugated systems.

New Organic Dyes Based on Biarylmethylene-Bridged Triphenylamine for Dye Sensitized Solar Cell

Three new organic dyes were synthesized and characterized for applications in dye-sensitized solar cells （DSSCs）. In these dyes, diarylmethylene-bridged triphenylarnine is the donor, and different acceptors and vinyl- thiophene are designed to get TBA-1, TBA-2 and TBA-3. Their photophysical, electrochemical and photovoltaic properties were investigated, and the effects of the acceptor structures as well as the linkage on these properties were evaluated. Results demonstrated that the vinylthiophene linkage between the donor and the acceptor is favor- able for improving light harvesting ability of TBA-2. In addition, the electrochemical impedance spectroscopy ex- periments suggest larger Rrec and longer electron lifetime of TBA-2. Therefore, it outperforms the other dyes, exhib- iting the highest power conversion efficiency of 3.87%, with Jsc of 8.25 mAocm-2 and Voc of 666 mV. Unfortunately, the TBA-3 with three acceptor groups only shows efficiency of 3.52%, indicating that the design of increasing ac- ceptor groups plays little role on enhancing the solar cell efficiency.

Sulfonyldibenzene-based hole-transporting materials for efficient n-i-p perovskite solar cells

Organic hole-transporting materials(HTMs)are an essential component in conventional perovskite solar cells(PSCs).In this work,two sulfonyldibenzene-based molecules,named CS-04 and CS-05,are synthesized and employed as HTMs in n-i-p PSCs.In comparison with CS-04,the carbazole-substituted methoxytriphenylamine(Cz MOTPA)group in CS-05 exhibits an increased degree of molecular distortion,thus endowing CS-05 with excellent solvent solubility and film-formation ability.Moreover,CS-05 shows a high hole mobility,superior hole extraction and hole transporting properties.As a result,CS-05 yields impressive device performances with a high power conversion efficiency(PCE)of 20.15%,while that of CS-04 based device is 19.50%,which is comparable to that of the Spiro-OMe TAD based control device(19.59%).This finding illustrates the potential of sulfonyldibenzene-based molecules for the applications in PSCs,and also provides a novel avenue to improve the performances and stability of PSCs by tailoring the sulfonyldibenzene-based molecules.