Photovoltaics-polymers-side

By tuning the side chains or/and backbone of conjugated polymers, a variety of high-performance photovoltaic polymers have been developed and applied in PSCs in recent years. 

Attaching perylene moieties as side groups allows achievement of high concentration without affecting the electronic structure of the polymer backbone. Putting 16% perylene moieties as side chains predictably results in more efficient energy transfer, observed with polymer 360, both in solution and solid state (emission band at 599 nm). Although no PLED device with 360 has been reported, this material showed excellent performance in solar cells (external photovoltaic QE = 7%, in blend with PPV) [434]. 

Yang LQ, Zhou HX, You W (2010) Quantitatively analyzing the influence of side chains on photovoltaic properties of polymer-fullerene solar cells. J Phys Chem C 114 16793... 

We investigate the properties of two different type-II heterojunction systems that sit on either side of the exciton destabilization threshold blends of the hole-accepting TFB with the electron-accepting F8BT that show excellent LED performance (see below) and blends of the hole-accepting PFB with F8BT that make poor LEDs but show promise for use as photovoltaic diodes [27]. These and related polymers have been used extensively for LEDs [10, 26, 36]. 

It is also found that the position of alkyl chain has an obvious effect on the molecular weights and photovoltaic performance of the resulting polymers. Gao et al. synthesized a series of internal donor-acceptor type of copolymers 78 containing BT and four thiophenes incorporating side chains on different position as shown in Fig. 2.4B (Wang et al., 2009). 

N.S., Hoppe, H., 2012. Charge carrier mobility, photovoltaic, and electroluminescent properties of anthracene-based conjugated polymers bearing randomly distributed side chains. J. Polym. Sci. Part A Polym. Chem. 50, 3425-3436. 

Li, G., Zhao, B., Kang, C., Lu, Z., Li, C., Dong, H., Hu, W, Wu, H., Bo, Z., 2015a. Side chain influence on the morphology and photovoltaic performance of 5-fluoro-6-alkyloxybenzothiadiazole and benzodithiophene based conjugated polymers. ACS Appl. Mater. Interfaces 7,10710-10717. 

Zhang, Z.-G., Li,Y., 2014. Side-chain engineering ofhigh-efficiency conjugated polymer photovoltaic materials. Sci. China Chem. 58,192-209. 

Rathgeber S, Perlich J, KAhnlenz F, TArk S, Egbe DA, Hoppe H, et al. Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynyl-ene)-alt-poly(p-arylene-vinylene) PCBM bulk-heterojunction solar cells. Polymer 2011 52(17) 3819-26. 

---