Anion‐Doped Thickness‐Insensitive Electron Transport Layer for Efficient Organic Solar Cells. Issue 22 (15th May 2022)

• Record Type: Journal Article
• Authors: Liu, Zixian; Tang, Haoran; Feng, Hexiang; Tan, Ching‐Hong; Liang, Youcai; Hu, Zhicheng; Zhang, Kai; Huang, Fei; Cao, Yong
• Other Names: Zhang Xin guestEditor.; Huang Hui guestEditor.
• Is Part Of: Macromolecular rapid communications. Volume 43:Issue 22(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-15
• Subjects: anion doping -- electron transport layers -- organic solar cells -- water/alcohol‐soluble conjugated polyelectrolytes; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202200190
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: In organic solar cells, interfacial materials play essential roles in charge extraction, transportation, and collection. Currently, highly efficient and thickness‐insensitive interfacial materials are urgently needed in printable large area module devices. Herein, water/alcohol‐soluble conjugated polyelectrolyte PFNBT‐Br, with medium bandgap based on benzothiadiazole, are doped by two alkali metal sodium salts, NaH2 PO2, Na2 C2 O4 with different counter anions, to pursue high efficiency and thickness‐insensitive electron‐transport layers. Results show that the doping of electron‐transport material can effectively promote the performance of the devices. Moreover, electron‐transport layers doped by these salts with different counter anions show different behaviors in performances. Among which, the salt with oxalate anion C2 O4 2− (also named Ox 2− ) shows much better device performance than the salt with hypophosphite anion (H2 PO2 − ), especially under the thick film condition (e.g., 50 nm). The greatly enhanced performances of interfacial material doped by Ox 2− are due to reduced series resistance between the active layer material and the electrode, reduced dark‐current, improved charge transport, and extraction efficiency, and decreased charge recombination for the devices at thick‐film condition. These results demonstrated that n‐doping could be a great potential strategy for making thickness‐insensitive interfacial layers, besides, the performances can be further improved by carefully selecting salts. Abstract : Two alkali metal sodium salts NaH2 PO2 and Na2 C2 O4 are doped into medium bandgap polyelectrolyte PFNBT‐Br to pursue high efficiency and thickness‐insensitive electron‐transport layers. The results show that devices with PFNBT‐Br retain only 47% in PCE when ETL thickness increases from 5 to 50 nm, while for PFNBT‐H2 PO2 and PFNBT‐Ox, the retain ratio is improved to 61% and 86%.