A team from Sweden’s Umeå University has developed an efficient vertical charge transport in semiconducting polymers. They say their process enhances the charge transport in polymers by 1,000 times. Applications for the process could enhance charge transport in OPV and OLED film and electronic devices. The scientists say they have controlled chain orientation and high mobility in the vertical direction for the first time.

Depiction of vertically aligned chains in organic semiconducting polymer.Traditionally, doping is required to enhance transport and mobility, which can change the structure of the polymer. These impurities introduced to the polymer enhance its electrical properties, but can change other properties. Rather than doping, the researchers controlled the orientation and formation of crystallites, thereby achieving the improved charge transport mobility. With the development of a method that aligns the chains in the polymer vertically, electric charges travel along the backbone of the chain, achieving the gain. The controlled chain and crystalline orientation alone were responsible for the success, they say.

Using nanoscopic electrical measurements, the researchers measured mobility, which averaged 3.1 cm²/V.s, the highest measured in P3HT. That measurement nears the theoretical estimation of the maximum mobility in P3HT. Stanford University’s National Accelerator (SLAC) used synchrotron X-ray diffraction to verify crystallinity and molecular packing characterization. Their tests confirmed that the high mobility was solely due to the reorientation of the polymer chains and crystallites, which achieved the fast charge transport along the backbones of the polymer.

The researchers say the simple process is easy to replicate and inexpensive, opening the door to applications in organic opto-electronic devices, photovoltaiccells, light emitting diodes, lasers and more.