Solution-processed pH-neutral Conjugated Polyelectrolyte Improves Interfacial Contact in Organic Sol

• 作 者: HuiqiongZhou[1]YuanZhang[2]Cheng-KangMai[2]JasonSeifter[2]Thuc-QuyenNguyen[2]GuillermoC.Bazan[2]AlanJ.Heeger[2]
• 机 构: Center for Polymers and Organic Solids,University of California,Santa Barbara,Santa Barbara,CA 93106
• 出 处: The 6th International Conference on Nanoscience and Technolo
• 发表日期: 2015年期

　　Bulk heterojunction(BHJ)solar cells comprising conjugated polymer donor and fullerene acceptor offer promising advantages such as low cost,light weight,and flexibility.[1] In addition to new materials design and morphology optimization,interface engineering on BHJ solar cells is fundamentally important to enhance the power conversion efficiency(PCE)and device stability.[2] To improve the charge selectivity at the electrodes and minimize the energy barrier for charge extraction,a hole-transporting layer(HTL)with electron-blocking properties is inserted between the anode and BHJ active layer,and an electron-transporting layer(ETL)with hole-blocking properties is inserted between the cathode and BHJ active layer.The metallic polymer PEDOT:PSS is the most commonly used HTL material for organic BHJ solar cells,because of its solution processability,work function,sufficient conductivity,and high optical transparency in the visible-NIR regime.[3] However,the intrinsic acidic nature of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS)hole-transporting layer(HTL)induces interfacial protonation and limits the device performance in organic solar cells based on basic pyridylthiadiazole units.By utilizing a pH neutral,water/alcohol soluble conjugated polyelectrolyte CPE-K as the HTL in p-DTS(PTTh2)2:PC71BM solar cells,a 60%enhancement in PCE has been obtained with an increased Vbi,reduced Rs,and improved charge extraction.These effects originate from the elimination of interfacial protonation and energy barrier compared with the PEDOT:PSS HTL.