In the last years, the semiconducting polymers have reached an increasing importance for the production of organic-based photovoltaic solar cells (OPV)s. In fact, these materials are easy to process and quite inexpensive. However, the control of the nanoscale morphology or microstructure of the active layer in hybrid solar cells is critical to ensure high device performance. We report on the synthesis of a new thiophenic monomer, functionalized in the side chains with a molecule showing a liquid crystal (LC) behavior, i.e. the 3-[6-(4-oxy-4'-cyanobiphenyl)hexyl]thiophene (T6CB). It has been obtained using a SN2 reaction on the thiophenic intermediate 3-(6-bromohexyl)thiophene (Figure 1), with good yield (90%). Since the homopolymer of T6CB was insoluble in common organic solvents, the monomer has been copolymerized with 3-hexylthiophene to give a soluble and filmable copolyer which has been exploited for the assembling of a bulk heterojunction polymeric solar cell. The spontaneous orientation of cyano-biphenyl moieties should lead to a well-ordered morphology when subjected to a process of thermal annealing, thus favoring the alignment of the macromolecular chains [ ]. In fact, COP has shown a LC behavior, as confirmed by the images obtained with the optical microscope in polarized light. Lastly, after a suitable annealing procedure, the power conversion efficiency of COP reached the 3.56%, evidencing a significant increase with respect to the un-annealed counterpart (2.95%).
A new polythiophene with LC side chains for BHJ solar cells
DI NICOLA, FRANCESCO PAOLO;LANZI, MASSIMILIANO;SALATELLI, ELISABETTA
2015
Abstract
In the last years, the semiconducting polymers have reached an increasing importance for the production of organic-based photovoltaic solar cells (OPV)s. In fact, these materials are easy to process and quite inexpensive. However, the control of the nanoscale morphology or microstructure of the active layer in hybrid solar cells is critical to ensure high device performance. We report on the synthesis of a new thiophenic monomer, functionalized in the side chains with a molecule showing a liquid crystal (LC) behavior, i.e. the 3-[6-(4-oxy-4'-cyanobiphenyl)hexyl]thiophene (T6CB). It has been obtained using a SN2 reaction on the thiophenic intermediate 3-(6-bromohexyl)thiophene (Figure 1), with good yield (90%). Since the homopolymer of T6CB was insoluble in common organic solvents, the monomer has been copolymerized with 3-hexylthiophene to give a soluble and filmable copolyer which has been exploited for the assembling of a bulk heterojunction polymeric solar cell. The spontaneous orientation of cyano-biphenyl moieties should lead to a well-ordered morphology when subjected to a process of thermal annealing, thus favoring the alignment of the macromolecular chains [ ]. In fact, COP has shown a LC behavior, as confirmed by the images obtained with the optical microscope in polarized light. Lastly, after a suitable annealing procedure, the power conversion efficiency of COP reached the 3.56%, evidencing a significant increase with respect to the un-annealed counterpart (2.95%).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
