A series of small compound materials based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) with three different alkyl side chains were synthesized and used for organic photovoltaics. These small compounds had different alkyl branches (i.e., 2-ethylhexyl (EH), 2-butyloctyl (BO), and 2-hexyldecyl (HD)) attached to DPP units. Thin films made of these compounds were characterized and their solar cell parameters were measured in order to systematically analyze influences of the different side chains of compounds on the film microstructure, molecular packing, and hence, charge-transport and recombination properties. The relatively shorter side chains in the small molecules enabled more ordered packing structures with higher crystallinities, which resulted in higher carrier mobilities and less recombination factors; the small molecule with the EH branches exhibited the best semiconducting properties with a power conversion efficiency of up to 5.54% in solar cell devices. Our study suggested that tuning the alkyl chain length of semiconducting molecules is a powerful strategy for achieving high performance of organic photovoltaics.
HOIP as a sensitizer were about 3.13% for bromide compound (CH 3 NH 3 PbBr 3 ) and 3.81% for iodide compound (CH 3 NH 3 PbI 3 ). In 2011, Im et al [2] reported the efficiency of ~4.7% for a photovoltaic cell containing HOIP as quantumdot-sensitizer. In 2012, Lee et al used HOIP materials as the active layer material for the first time; it was one of the most important events in the HOIP photovoltaics field. Lee et al reported that the efficiency of their HOIP photovoltaic cell was 10.9% in a single junction device [3]. Numerous research results of HOIP photovoltaic cells have been reported since then. In 2016, a much higher efficiency of 22.
Post-treatment processes improve the performance of organic photovoltaic devices by changing the microscopic morphology and configuration of the vertical phase separation in the active layer. Thermal annealing and solvent vapor (or chemical) treatment processes have been extensively used to improve the performance of bulk-heterojunction (BHJ) organic photovoltaic (OPV) devices. In this work we introduce a new post-treatment process which we apply only electrical voltage to the BHJ-OPV devices. We used the commercially available P3HT [Poly(3-hexylthiophene)] and PC61BM (Phenyl-C61-Butyric acid Methyl ester) photovoltaic materials as donor and acceptor, respectively. We monitored the voltage and current applied to the device to check for when the post-treatment process had been completed. This electrical treatment process is simpler and faster than other post-treatment methods, and the performance of the electrically treated solar cell is comparable to that of a reference (thermally annealed) device. Our results indicate that the proposed treatment process can be used efficiently to fabricate high-performance BHJ-OPV devices.
Two novel triple bond containing polymers were investigated as potential candidates for new photocrosslinkable materials with solvent resistance and a hydrophobic nature, and can be used in solution processed multilayer organic electronic devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.