Effect Of Electric Field And Solution Annealing On Conformation Of PFO

Conjugated polymers are emerging as promising materials for making flexible electronics and photonics.Among them,poly(9,9-dioctylfluorene)(PFO)as a blue-lightemitting polymer is attracting great attention due to its excellent charge transport properties and highly efficient photoluminescence.Optoelectronic devices based on PFO have a wide range of applications in organic light-emitter diodes,lasers,solar cells and field effect transistors.The performance of the devices to a large extent is determined by the conformation of the conjugated polymers.Compared with the ?-phase of PFO,the structures based on the ?-phase exhibit a higher charge-carrier mobility and a high efficiency.For applications such as light emitting diodes and electrically pumped organic lasers,high charge-carrier mobility is critical.Therefore,increasing the fraction of the ?-phase in films and developing PFO crystals are an issue of great importance.The focus of this study is to explore effective approaches to improve the fraction of ?-phase in PFO films.In the first part,solution annealing by immersing PFO film in the mixture of a good solvent and a poor solvent is examined.In this part,the influences of the volume ratio of solvents,immersing time and temperature on the formation of ?-phase in PFO film are examined respectively.As results,the optimum volume ratio,temperature and processing time are determined.In the second part,we study the influence of the alternating electric field on the crystallization process of PFO.In this experiment,crystallization processes of PFO are observed at different voltage,frequency and the concentration of PFO solution.It shows that the alternating electric field can effectively improve the size and the quality of PFO crystals.