Metal Ion/Dendrimer Complexes with Tunable Work Functions in a Wide Range and Their Application as Electron‐ and Hole‐Transport Materials of Non‐Fullerene Organic Solar Cells. (22nd June 2018)

• Record Type: Journal Article
• Authors: Yu, Zhimeng; Li, Bichen; Ouyang, Jianyong
• Is Part Of: Advanced functional materials. Volume 28:Number 33(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-06-22
• Subjects: ITO -- metal complexes -- organic solar cells -- poly(amido amine) -- PAMAM -- work function; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201802554
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: The work functions of electrodes can be modified by adding charge transport layers to have good energy level matching with the active materials for organic solar cells (OSCs). Usually, a certain material gives rise to one definite work function of an electrode. In this work it is demonstrated that complexes of poly(amido amine) (generation 3) (PAMAM) with Cu 2+ can continuously tune the work function of indium tin oxide (ITO) in a range of 4–5 eV by controlling the ratio of Cu 2+ to PAMAM. PAMAM can lower the work function of ITO from 4.60 to 4.07 eV, while Cu 2+ ‐PAMAM can increase the work function. The work function increase depends on the Cu 2+ ‐to‐PAMAM molar ratio, and the work function can be up to 4.96 eV. The Cu 2+ effect is ascribed the Cu 2+ ‐caused change in the dipole moment of PAMAM. Moreover, this method can be used to continuously modify the work function of other materials, including Ag, Au, poly(3, 4‐ethylenedioxythiophene):polystyrene sulfonate, and reduced graphene oxide. In addition, PAMAM and Cu 2+ ‐PAMAM are investigated as the charge collection buffer materials of non‐fullerene OSCs of poly[(2, 6‐(4, 8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)‐benzo[1, 2‐b:4, 5‐b′]dithiophene))‐alt‐(5, 5‐(1′, 3′‐di‐2‐thienyl‐5′, 7′‐bis(2‐ethylhexyl)benzo[1′, 2′‐c:4′, 5′‐c′]dithiophene‐4, 8‐dione))]: 3, 9‐bis(2‐methylene‐(3‐(1, 1‐dicyanomethylene)‐indanone))‐5, 5, 11, 11‐tetrakis(4‐hexylphenyl)‐dithieno[2, 3‐d:2′, 3′‐d′]‐s‐indaceno[1, 2‐b:5, 6‐b′]dithiophene). The power conversion efficiency can reach 9.2%, which is comparable to that using conventional charge transport materials. Abstract : The work function of conductors including indium tin oxide (ITO), Ag, Au, poly(3, 4‐ethylenedioxythiophene):polystyrene sulfonate, and reduced graphene oxide can be continuously modified by simply varying the Cu 2+ to poly(amido amine) (generation 3) (PAMAM) ratio. The work function variation is related to the interaction between the conductors and Cu 2+ ‐PAMAM. ITO/PAMAM and ITO/Cu 2+ ‐PAMAM can be used as the buffer materials of organic solar cells to effectively collect electrons and holes, respectively.