Phenolic additives and their effects on blend morphologies of bulk heteojunctions

• Main Authors: Fang-Lin Gong, 龔芳琳
• Other Authors: Wen-Yao Huang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/21148072049002224866

碩士 === 國立中山大學 === 光電工程學系研究所 === 99 === Controlling the blend morphology is one of the ways to achieve high power conversion efficiency in organic bulk heterojunction (BHJ) photovoltaic device. One sample yet effective method is “ additive” approach, which involves the addition of a small concentrations of additive into the blend of donor/acceptor dissolved in solution. When adding small concentrations of additives in solution, we can change the donor/acceptor of internal micro-structure and films of morphology. In this work, we performed a systematic study of the effect of nanocrystals of phenolic additives, such as the small concentrations of 4,4''-Sulfonyldiphenol(BPDT), 4,4''-Dihydroxybiphenyl(BP) and Biphenyl-4,4’-dithiol(BPS), on the nanoscals phase separation of and P3HT:PCBM blends and consequently, the power conversion efficiency(PCE) of the devices. The extent of the additive-induced phase separation and crystallize of P3HT is related to the additive acidity constant (pKa) and the degree of interaction between the additive and P3HT/PCBM, as evident from X-ray diffractmeter, UV-Vis spectrometer, Raman spectrometer and current density-voltage characteristic data. Lastly, PCE as increasing as 25% and short current increasing as 15% can be achieved in an optimally phase-separated blend due to an improvement in the charge dissociation and a dcrease in bimolecular recombination and parallel resistance.