High-performance asymmetric small molecular donor materials based on indenothiophene for solution-processed organic solar cells

Two novel asymmetric organic small molecules of IT(2FBT-T3Cz)_2and IT(2FBT-TT3Cz)_2with an indenothiophene(IT)central donor core,fluorinated benzothiadiazole(2FBT)as acceptor and 3-carbazole(Cz)unit as terminal group were designed and synthesized as the donor materials in organic solar cells(OSCs).The thermal,optical absorption,electrochemical property,hole–electron mobility,film morphology were thoroughly studied.Using PC_(71)BM as an electron acceptor,without any additive and thermal annealing(TA)treatment,the IT(2FBT-T3Cz)_2-based cells showed a promising power conversion efficiency(PCE)of5.81%and the IT(2FBT-TT3Cz)_2-based cells exhibited a PCE of 4.39%.Our results demonstrate that the IT-based asymmetric small molecules can be developed as a promising class of donor materials for highperformance OSCs.

Truxene-based Hole-transporting Materials for Perovskite Solar Cells

Three star-shaped truxene-based small molecules（namely TXH,TXM,TXO） were synthesized,characterized and used as hole-transporting materials（HTMs） for perovskite solar cells（Pv SCs）. The device based on TXO delivered a respectable power conversion efficiency（PCE） of 7.89% and a high open-circuit voltage（Voc） of 0.97 V,which far exceeded the values of the devices based on other two small molecules. The highest PCE for the device based on TXO is mainly contributed from its lowest series resistance（Rs） value and largest short-circuit current（Jsc） value under the same circumstances. All these results indicate that TXO is a promising HTM candidate for Pv SCs.

Highly stable perovskite solar cells with a novel Ni-based metal organic complex as dopant-free hole-transporting material

Hole-transporting material(HTM)plays a paramount role in enhancing the photovltaic performance of perovskite solar cells(PSCs).Currently,the vast majority of these HTMs employed in PSCs are organic small molecules and polymers,yet the use of organic metal complexes in PSCs applications remains less explored.To date,most of reported HTMs require additional chemical additives(e.g.Li-TFSI,t-TBP)towards high performance,however,the introduction of additives decrease the PSCs device stability.Herein,an organic metal complex(Ni-TPA)is first developed as a dopant-free HTM applied in PSCs for its facile synthesis and efficient hole extract/transfer ability.Consequently,the dopant-free Ni-TPAbased device achieves a champion efficiency of 17.89%,which is superior to that of pristine Spiro-OMeTAD(14.25%).Furthermore,we introduce a double HTM layer with a graded energy bandgap containing a Ni-TPA layer and a CuSCN layer into PSCs,the non-encapsulated PSCs based on the Ni-TPA/CuSCN layers affords impressive efficiency up to 20.39%and maintains 96%of the initial PCE after 1000 h at a relative humidity around 40%.The results have demonstrated that metal organic complexes represent a great promise for designing new dopant-free HTMs towards highly stable PSCs.

“Mutually Doped”Conjugated Polyelectrolyte-Polyoxometalate Complex as Hole Transporting Material for Efficient Organic Solar Cells

Comprehensive Summary Compared to electron transporting layer materials,the species and numbers of hole transporting layer(HTL)materials for organic solar cells(OSCs)are rare.The development of HTL materials with excellent hole collection ability and non-corrosive nature is a long-standing issue in the field of OSCs.Herein,we designed and synthesized a series of conjugated polyelectrolytes(CPEs)with continuously varied energy levels toward HTL materials for efficient OSCs.Through a“mutual doping”treatment,we obtained a CPE composite PCT-F:POM with a WF of 5.48 eV and a conductivity of 1.56х10^(-3)S/m,meaning that a good hole collection ability can be expected for PCT-F:POM.The OSC modified by PCT-F:POM showed a high PCE of 18.0%,which was superior to the reference device with PEDOT:PSS.Moreover,the PCT-F:POM-based OSC could maintain 91%of the initial PCE value after storage of 20 d,meaning that the long-term stability of OSCs is improved by incorporating the PCT-F:POM HTL.In addition,PCT-F:POM possesses good compatibility with large-area processing technique;i.e.,a PCT-F:POM HTL was processed by the blade-coating method for fabricating 1 cm^(2)OSC,and a PCE of 15.1%could be achieved.The results suggest the promising perspective of PCT-F:POM in practical applications.

New advances in small molecule hole-transporting materials for perovskite solar cells

Organic π-functional molecules are the foundation and basic component of organic optoelectronic devices.For example,for ideal carrier transporting materials,extended π-conjugation and ordered π-πstacking are necessary to enhance the charge mobility and achieve desirable results.As a promising way to convert sunlight into electricity,organometal halide perovskite solar cells（PSCs） have captured a lot of attention due to its predominant merits especially in the aspect of remarkable photovoltaic performance and much potentially low production cost.For conventional planar PSC structure,hole-transporting layer which typically consists of organic π-functional materials plays a key role in suppressing holeelectron pair recombination,promoting charge transporting and ensuring ohmic contact of back electrode.Considering the key roles of HTMs and its soaring progress in recent years,here,we will summarize recent progress in small organic π-functional materials from its diverse functions in PSCs.Besides,aiming to further promote the development of organic π-functional molecules and HTMs,a promising direction toward highly efficient HTMs will also be discussed.

Pyridine-triphenylamine hole transport material for inverted perovskite solar cells

In the light of superior interaction between pyridine unit and perovskite,a facile star-shaped triphenylamine-based hole transport material(HTM)incorporating pyridine core(coded as H-Pyr)is designed and synthesized.A reference HTM with benzene core,coded as H-Ben,is also prepared for a comparative study.The effects of varying core on HTMs are investigated by comparing the photophysical,electrochemical and hole mobility properties.It is found that pyridine core exhibits better conjunction and decreased dihedral angles with triphenylamine side arms than that of benzene,leading to obviously better hole mobility and well-matched work function.The perovskite film prepared on H-Pyr also shows improved crystallization than on H-Ben.Photoluminescence and electrochemical impedance studies indicate improved charge extraction and reduced recombination in the H-Pyr-based perovskite solar cells.Consequently,H-Pyr-based device exhibits higher efficiency than H-Ben-based one.After doping with a Lewis acid,tris(pentafluorophenyl)borane,H-Pyr-based device delivers a champion efficiency of 17.09%,which is much higher compared with 12.14% of the device employing conventional poly(3,4-ethy lenedioxythiophene)polystyrene sulfonate(PEDOT:PSS)as HTM.Moreover,the H-Pyr-based device displays good long-term stability that the power conversion efficiency remains over 80% of the initial value after storage in ambient(relative humidity=50±5%)for 20 days.

三种同分异构的双苯并吩噻嗪材料的合成、理论计算及光物理性质

吩噻嗪及其衍生物材料是一类重要的多环芳烃材料,在光电子领域有着广泛的应用。其中,基于苯并噻嗪材料的研究相对较少。在本文中,我们分别在吩噻嗪的1,2-、2,3-和3,4-位引入苯基,制备了三种同分异构的双苯并吩噻嗪化合物D-PTZa、D-PTZb和D-PTZc,研究了它们的构效关系,并与双吩噻嗪化合物(D-PTZ)进行了对比。研究发现,D-PTZb和D-PTZc的HOMO和LUMO分布与D-PTZ的类似;对于D-PTZa,其1,2-位引入的苯基与中间的苯环空间张力较大,造成空间结构极度扭曲,性质比较特殊。并苯的引入可以有效增加分子的共轭长度,使得最大吸收波长发生红移;在2,3-位引入苯基可以有效地稳定HOMO能级,使基于π→π*跃迁的能隙稍有增大,呈现蓝光发射,溶液的荧光量子产率为1.7%;而在3,4-位引入苯基使LUMO分布更加趋向于线型,从而使LUMO更加稳定,使基于π→π*跃迁的能隙降低,其最大发射峰位于520 nm处,呈现黄绿光发射,溶液荧光量子产率为13%。此外并入苯环之后,空间张力增大,化合物的分解温度降低。我们的分子设计和结构–性质关系的研究可以为设计新的吩噻嗪材料提供基础指导。

Progress in small-molecule luminescent materials for organic light-emitting diodes

Organic light-emitting diodes （OLEDs） have been extensively studied since the first efficient device based on small molecular luminescent materials was reported by Tang. Organic electroluminescent material, one of the centerpieces of OLEDs, has been the focus of studies by many material scientists. To obtain high luminosity and to keep material costs low, a few remarkable design concepts have been developed. Aggregation-induced emission （AIE） materials were invented to overcome the common fluorescence-quenching problem, and cross-dipole stacking of fluorescent molecules was shown to be an effective method to get high solid-state luminescence. To exceed the limit of internal quantum efficiency of conventional fluorescent materials, phosphorescent materials were successfully applied in highly efficient electroluminescent devices. Most recently, delayed flu- orescent materials via reverse-intersystem crossing （RISC） from triplet to singlet and the ＂hot exciton＂ materials based on hy- bridized local and charge-transfer （HLCT） states were developed to he a new generation of low-cost luminescent materials as efficient as phosphorescent materials. In terms of the device-fabrication process, solution-processible small molecular lumi- nescent materials possess the advantages of high purity （vs. polymers） and low procession cost （vs. vacuum deposition）, which are garnering them increasing attention. Herein, we review the progress of the development of small-molecule luminescent materials with different design concepts and features, and also briefly examine future development tendencies of luminescent materials.

Conjugated Polymers as Hole Transporting Materials for Solar Cells

In principle,conjugated polymers can work as electron donors and thus as low-cost p-type organic semiconductors to transport holes in photovoltaic devices.With the booming interests in high-efficiency and low-cost solar cells to tackle global climate change and energy shortage,hole transporting materials(HTMs)based on conjugated polymers have received increasing attention in the past decade.In this perspective,recent advances in HTMs for a range of photovoltaic devices including dye-sensitized solar cells(DSSCs),perovskite solar cells(PSCs),and silicon(Si)/organic heterojunction solar cells(HSCs)are summarized and perspectives on their future development are also presented.

无掺杂空穴传输材料在n-i-p型钙钛矿太阳能电池中的应用研究进展

钙钛矿太阳能电池(perovskite solar cells,PVSCs)因长期稳定性差和制造成本高难以实现工业化生产。其制备中最常用的空穴传输材料(hole-transporting materials,HTMs)为2,2′,7,7′-四[N,N-二(4-甲氧基苯基)氨基]-9,9′-螺二芴,需一定量吸湿添加剂以实现高效的空穴提取,导致对水敏感的钙钛矿层受到破坏。无掺杂HTMs避免了吸湿添加剂的使用,且成本低、合成步骤简单。综述了应用于n-i-p型PVSCs的YT5、M7-TFSI、P3HT、PBDB-Cz等高效率无掺杂有机小分子以及聚合物HTMs,提出了理想HTMs在器件性能、分子结构、合成条件、经济成本等方面的设计原则,并展望了无掺杂HTMs在PVSCs商业化过程中的应用前景。

White organic light-emitting devices fabricated by spin-coating molecular materials

White organic light-emitting device (WOLEDs) employing molecular mixed host (MH) is demonstrated by spin-coating.The spin-coated film functions as light-emitting layer and hole transporting layer,with the former formed by spin-coating solution containing MH of NPB (N.N'-Bis(naphthalene-1-yl)-N,N'-bis(phenyl)-benzidine) and MADN (2-methyl-9,10-di(2-naphthyl) anthracene),blue dye (4,4'-bis[2-(4-(N,N-diphenylamino)phenyl)vinyl]biphenyl) and yellow dye (5,6,11,12-tetraphenylnaphacene).The performances of the devices made with different mixed ratio of MH are investigated.It is found that the device performances depends on the MH ratio,and under the optimal NPB:MADN ratio (60:40),the WOLEDs show a maximum luminance of 24 671 cd/m2 and a current efficiency of 5.8 cd/A for the practical luminance of 1000 cd/m2.The effect of MH ratio on device performances can be attributed to the difference of hole mobility between the NPB and MADN.

Recent Progresses on Dopant-Free Organic Hole Transport Materials toward Efficient and Stable Perovskite Solar Cells

As the third generation new battery,the power conversion efficiency(PCE)of metal halide perovskite solar cells(PsCs)has increased from 3.8%in 2009 to 25.8%currently certified,which fully shows that they have great research value and development prospect.As one of the main components of high-efficiency PSCs,hole transport materials(HTMs)play an important role in extracting and transporting holes and inhibiting charge recombination.However,commonly used HTMs require doping,and the hygroscopicity and corrosiveness of the dopants will destroy the stability of PsCs and hinder their commercialization.Therefore,it is of great significance to develop dopant-free HTMs.

两种新型双极有机小分子发光材料的合成与发光

设计和合成了两种新的具有“双极(bipolar)”性质和发光性能的有机小分子化合物N-[4-(5-(2-苯基喹啉-4)-1,3,4-噁二唑-2)苯基]-N'-苯基-N,N'-二苯基-1,1'-联苯基-4,4'-二胺(TPDOPQ)和N,N'-双{4-[5-(2-苯基喹啉-4-基)-1,3,4-噁二唑-2]苯基}-N,N'-二苯基-1,1'-联苯基-4,4'-二胺[TPD(OPQ)2].用1HNMR,MS和元素分析进行了表征,研究了化合物的热稳定性和光致发光性质,并用循环伏安法测定了其电化学性能.结果表明,这两种合成的有机化合物同时具备空穴传导和电子输入双重功能,光致发光性能优良,热稳定性好,能形成均衡薄膜,因此可作为制作有机电致发光器件的候选材料.

有机分子电致发光材料进展

由于有机电致发光器件在彩色平板显示等领域具有极大的应用前景 ,已引起广泛的关注。与无机物相比 ,有机发光材料具有高荧光效率、颜色的广泛选择性及易成膜性。本文主要介绍近年来有机分子电致发光材料最新的发展 ,并特别讨论了齐聚物和含载流子传输单元的发光体。

有机空穴传输材料在钙钛矿太阳电池中的应用

有机-无机杂化钙钛矿太阳电池(PSCs)由于其诸多优点得到广泛关注,而有机固态空穴传输材料(HTMs)代替液体电解质使其得到飞速的发展,提升了电池的效率和稳定性,已经成为PSCs的重要组成部分。目前应用于PSCs的空穴传输材料分为有机空穴传输材料和无机空穴传输材料两大类。无机空穴传输材料的可选择范围较窄,对应器件的光电转换效率相对较低。开发各类能级匹配、空穴迁移率高的有机空穴传输材料是提高器件效率和稳定性的有效手段,成为相关领域的研究热点。本文依据相对分子质量的大小,将应用于PSCs中的有机空穴传输材料分为小分子类和聚合物类空穴传输材料,详细评述了有机空穴传输材料分子结构对PSCs光电转换效率、填充因子、开路电压、短路电流和稳定性的影响,并对其能级、空穴迁移率的高低、添加剂的使用等进行了讨论。最后详细论述了有机空穴传输材料未来的研究重点和发展趋势。

新型双极有机小分子化合物及其Al^(3+)配合物的合成与发光

合成了一种新的具有“双极”(b ipolar)性质的有机小分子蓝色发光材料2-(5-(4-(二苯胺基)苯基)-1,3,4-噁二唑-2-)苯酚[2(5-(4-(d iphenylam ino)phenyl)-1,3,4-oxad iazol-2-yl)phenol,HPOT],并以HPOT为配体,与铝离子配位,合成了三(2-(5-(4-(二苯胺基)苯基)-1,3,4-噁二唑-2-)苯酚)合铝[tri(2-(5-(4-(d iphe-nylam ino)phenyl)-1,3,4-oxad iazol-2-yl)phenonate)alum inum,A lPOT]配合物.用1H NMR、HRMS和元素分析进行了表征,并测定了两种化合物的光致发光性质和热稳定性.结果表明:两种新化合物的热稳定性好,光致发光性能优良,是制作有机电致发光器件的候选材料.

有机电致发光空穴传输材料研究进展

有机空穴传输材料的成膜性及其薄膜的热稳定性对于提高有机电致发光器件的效率和寿命具有重要的作用。本文按材料所含主体结构单元的不同 ,将有机空穴传输材料分为三类 ,从提高材料的成膜性及其热稳定性出发 ,详细介绍了近年来有机空穴传输材料的研究进展。

基于N-对甲氧苯基咔唑-2-乙烯基-8-羟基喹啉锌的白色和黄色有机电致发光器件的性能

通过研究新型荧光染料N-对甲氧苯基咔唑-2-乙烯基-8-羟基喹啉锌(MoBCzHQZn)的电致发光(EL)特性,发现MoBCzHQZn具有较强的发光特性和空穴传输特性,利用此特性制备了非掺杂型的有机电致白光器件和掺杂型的有机电致黄光器件.白光器件的结构为ITO/2T-NATA(20nm)/MoBCzHQZn(25nm)/NPBX(13nm)/BCP(8nm)/Alq3(34nm)/LiF(0.5nm)/Al,器件在15V电压下实现了白光发射,色坐标为(0.3719,0.3275),最大发光亮度为3414cd·m-2,在14V电压下的最大发光效率为1.69cd·A-1、黄光器件的结构为ITO/2T-NATA(20nm)/CBP:6%Ir(ppy)3:10%MoBCzHQZn(25nm)/TPBi:6%Ir(ppy)3(47nm)/LiF(0.5nm)/Al,器件在15V电压下实现了黄绿光发射,色坐标为(0.3590,0.5787),最大发光亮度为11073cd·m-2,在9V电压下的最大发光效率为2.51cd·A-1.

含芳胺和1,3,4-噁二唑的星型有机分子合成及光电性质

通过分子设计,采用多步反应合成了2种新型的具有＂双极＂（Bipolar）性质和发光性能的以N原子为中心的星型有机分子.用1HNMR,MS和元素分析进行了表征,研究了化合物的热稳定性和固体粉末的光致发光性质,并用循环伏安法测定了其电化学性能.结果表明,这种同时具备空穴传导和电子输入双重功能基团的星型有机小分子的光致发光性能优良（量子效率达到82%～95%）,热稳定性好,可以作为有机电致发光器件材料。

钙钛矿太阳能电池的研究进展

钙钛矿太阳能电池由纳米晶致密层、钙钛矿型光活性层CH3NH3Pb X3(X=Cl、Br、I)、空穴传输层及对电极组成。其中光活性层吸光材料的种类及其成膜技术、空穴传输层材料类型及结构设计是影响钙钛矿太阳能电池光电性能的重要因素。本文结合钙钛矿太阳能电池近年来的最新研究进展,对影响器件光电性能的关键因素:光吸收层、空穴传输层、工艺参数以及结构设计等进行综述,同时展望了钙钛矿太阳能电池未来的发展趋势。