Engineering fibrillar morphology for highly efficient organic solar cells

The power conversion efficiency(PCE)for single-junction organic solar cells(OSCs),wherein the photoactive layer is a typical bulk-heterojunction containing donor and acceptor materials,has surpassed 19%[1−4].The advance is ascribed to the development of Y-series non-fullerene acceptors(NFAs)[5,6]and polymer donors[7−13],and the refined control of the blend film morphology.

Combining chlorination and sulfuration strategies for high-performance all-small-molecule organic solar cells

Three small-molecule donors based on dithieno [2,3-d:2’,3 ’-d’]-benzo[1,2-b:4,5-b’] dithiophene(DTBDT)unit were designed and synthesized by side chain regulation with chlorinated or/and sulfurated substitutions(namely ZR1,ZR1-Cl,and ZR1-S-Cl respectively),along with a crystalline non-fullerene acceptor IDIC-4 Cl with a chlorinated 1,1-dicyanomethylene-3-indanone(IC) end group.Energy levels,molar extinction coefficients and crystallinities of three donor molecules can be effectively altered by combining chlorination and sulfuration strategies.Especially,the ZR1-S-Cl exhibited the best absorption ability,lowest higher occupied molecular orbital(HOMO) energy level and highest crystallinity among three donors,resulting in the corresponding all-small-molecule organic solar cells to produce a high power conversion efficiency(PCE) of 12.05% with IDIC-4 Cl as an acceptor.

有机太阳电池关键材料研究进展

有机太阳电池具有质量轻、柔性、印刷制备等优点,有巨大的应用潜力,从其诞生那一刻起便引起了学术界和工业界的广泛研究兴趣.历经25年的发展,有机太阳电池效率已突破18%,其快速进步得益于不断涌现的高性能新材料和器件制备技术,以及对电池活性层形貌、分子堆积和器件机理的深入理解.基于有机共轭结构的电子给体和电子受体材料是决定有机太阳电池性能的关键材料.本文将以给、受体材料的发展历程为主线,聚焦那些明星材料和里程碑工作,阐述高性能关键材料的分子结构演变和进化过程,最后展望其面临的挑战和未来发展方向.

Progress of the key materials for organic solar cells

Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight,flexibility and roll-to-roll fabrication.Nowadays,18%power conversion efficiency has been achieved in the state-of-the-art organic solar cells.The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies,and the deep understanding on film morphology,molecular packing and device physics.Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance.The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors.In this review,we focus on those star materials and milestone work,and introduce the molecular structure evolution of key materials.These key materials include homopolymer donors,D-A copolymer donors,A-D-A small molecular donors,fullerene acceptors and nonfullerene acceptors.At last,we outlook the challenges and very important directions in key materials development.

三维表面活性剂-石墨烯复合阴极界面材料在有机太阳能电池中的应用

低沸点绿色溶剂中分散石墨烯可广泛应用于涂料、导电油墨、电池、电子产品和太阳能电池等领域.研究发现,在乙醇溶液中,两种三维阴极界面材料POSSFN和ADMAFN分散石墨烯的浓度可达到0.97–1.18 mg mL^-1,通过计算得知这两种材料在石墨烯表面具有较大的吸附能.通过ESR、Raman、SKPM和XPS等测试手段证实,POSSFN侧链上的氨基能够与石墨烯发生n-掺杂作用;而AD-MAFN与石墨烯之间能够形成偶极相互作用.两种三维界面修饰-石墨烯复合材料(POSSFN-G和ADMAFN-G)均可作为阴极界面修饰材料应用于有机太阳能电池中,并使基于PM6:Y6光活性层的有机太阳能电池的能量转换效率(PCE)提高到了15.9%–16.1%,其中基于存在偶极相互作用的复合材料ADMAFN-G阴极修饰层的有机太阳能电池的PCE达到16.11%;使用存在n-掺杂作用的POSSFN-G阴极修饰层的器件,在厚膜状态下依然可获得较高的能量转换效率.

High electron mobility fluorinated indacenodithiophene small molecule acceptors for organic solar cells

Indacenodithiophene(IDT)derivatives are kinds of the most representative and widely used cores of small molecule acceptors(SMAs)in organic solar cells(OSCs).Here we systematically investigate the influence of end-group fluo rination density and position on the photovoltaic properties of the IDT-based SMAs IDIC-nF(n=0,2,4).The absorption edge of IDIC-nF red-shifts with theπ-πstacking and crystallinity improvement,and their electronic energy levels downshift with increasing n.Due to the advantages of J_(sc)and FF as well as acceptable V_(oc),the difluorinated IDIC-2 F acceptor based OSCs achieve the highest power conversion efficiency(PCE)of 13%,better than the OSC devices based on IDIC and IDIC-4 F as acceptors.And the photovoltaic performance of the PTQ10:IDIC-2 F OSCs is insensitive to the active layer thickness:PCE still keep high values of 12.00%and 11.46%for the devices with active layer thickness of 80 and 354 nm,respectively.This work verifies that fine and delicate modulation of the SMAs molecular structure could optimize photovoltaic performance of the corresponding OSCs.Meanwhile,the thickness-insensitivity property of the OSCs has potential for large-scale and printable fabrication technology.

Single-wall carbon nanotube-containing cathode interfacial materials for high performance organic solar cells

Water/alcohol soluble cathode interfacial materials(CIMs)are playing important roles in optoelectronic devices such as organic light emitting diodes,perovskite solar cells and organic solar cells(OSCs).Herein,n-doped solution-processable single-wall carbon nanotubes(SWCNTs)-containing CIMs for OSCs are developed by dispersing SWCNTs to the typical CIMs perylene diimide(PDI)derivatives PDIN and PDINO.The Raman and X-ray photoelectron spectroscopy(XPS)measurement results illustrate the ndoped behavior of SWCNTs by PDIN/PDINO in the blend CIMs.The blended and n-doped SWCNTs can tune the work function and enhance the conductivity of the PDI-derivative/SWCNT(PDI-CNT)composite CIMs,and the composite CIMs can regulate and down-shift the work function of cathode,reduce the charge recombination,improve the charge extraction rate and enhance photovoltaic performance of the OSCs.High power conversion efficiency(PCE)of 17.1%and 17.7%are obtained for the OSCs based on PM6:Y6 and ternary PM6:Y6:PC_(71) BM respectively with the PDI-CNTcomposites CIMs.These results indicate that the ndoped SWCNT-containing composites,like other n-doped nanomaterials such as zero dimensional fullerenes and two dimensional graphenes,are excellent CIMs for OSCs and could find potential applications in other optoelectronic devices.