We demonstrate that the morphology of poly(3-hexyl thiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT-PCBM) bulk heterojunctions (BHJ) could be tuned by the 4-cyano-4'-pentylterphenyl (5CT) liquid crystalline molecules under electric field assisted treatment for enhanced solar cell performance. The miscibility and interactions between the components were carefully studied, showing that 5CT could induce the crystallization of P3HT to form edge-on structures in ternary blends after electric field assisted treatment as revealed by grazing-incidence wide-angle X-ray diffraction (GIXRD). The PCBM and 5CT are supposed to form the rod-like complexes, and the nanorods could orient to the direction of electric field, accompanied by the homogeneous distribution of nanorods in diameters of about 30 nm at an electric field of 600 V mm(-1). The sizes of PCBM clusters and complexes are dependent on the 5CT doping ratios and intensity of electric field according to grazing-incidence small-angle X-ray scattering (GISAXS) analysis. When the active layers were processed under the atmospheric environment, the power conversion efficiency (PCE) could reach 3.5% at 5CT weight fraction of 6 wt% after treatment by an electric field of 600 V mm(-1), in contrast to the PCE value of 2.4% for a pristine P3HT-PCBM blend. This work provides an attractive strategy for manipulating the nanostructure of BHJ layers and also increases insight into morphology evolution when liquid crystalline molecules are incorporated into BHJs.

P3BT nanowires induce the crystallization of P3HT and the aggregation of PC61BM molecules, facilitating charge transportation.

A series of novel poly[(butylene succinate)-co-diolisobutyl]-[ polyhedral oligomeric silsesquioxane] (PBS-POSS) copolyestershave been synthesized for the first time directly from diacid and diols via melting polycondensation. Both PBS and POSS segments crystallized as revealed by X-ray diffraction, and the crystallization of PBS was found to be retarded by the incorporation of POSS into PBS chains based on differential scanning calorimetry and rheological results. Moreover, the copolyester containing 3 mol% POSS formed organogels in chloroform by the treatment of shear flow and was more thermally stable than the pristine sample, due to formation of a physically crosslinked network caused by the crystallization of POSS into crystals of larger sizes.

The poly(3-hexylthiophene):[6, 6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction organic photovoltaics (BHJ OPVs) showed a maximum value of 3.5 % by incorporating of 6 wt% nematic liquid crystals (NLCs) of 4-octyloxy-4 0 -cyanobiphenyls (8OCB) after annealing at the temperature of 70°C in liquid crystalline transitions. The 8OCB was immiscible with P3HT, and the melting temperature of P3HT was not influenced at 8OCB doping amount below 10 wt%. Based on the UV-vis analysis, the conjugation length and chain order of P3HT should be the highest at 8OCB content of 6 wt% after annealing at 70°C. The reflection peak of P3HT shifted to lower positions as the annealing temperature increasing from 70 to 130°C, indicating that PCBM and 8OCB molecules could be incorporated into the lamellar spacing of P3HT crystallites at high annealing temperatures. The improvement of the solar cell device after annealing at 70°C is probably due to the optimized phase separation morphology and relatively higher hole mobility in P3HT:PCBM:8OCB system. The 8OCB molecules in the liquid crystalline state are supposed to be a good template for the crystallization of P3HT, as well as the phase separation between P3HT and PCBM.

The influence of the polystyrene of different tacticities on the morphology, phase structure, and photovoltaic properties of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend has been extensively investigated. The atactic polystyrene (aPS) immiscible with P3HT tended to form the phase-separated and columnar structure at low aPS weight ratio. Besides, the aPS could migrate to the surface of the films with PCBM phase distributing in the interfaces between P3HT and aPS domains at high aPS weight ratio of 75 wt %. The syndiotactic polystyrene (sPS) immiscible with P3HT could induce the crystallization of P3HT at low weight ratio of 3 wt %. The device based on aPS/P3HT/PCBM ternary blend showed of power conversion efficiency (PCE) of 1.2% even at aPS weight ratio of 50 wt %. However, the device based on sPS/P3HT/PCBM exhibited a sharp decrease in PCE value from 2.3% to 0.6% at sPS weight ratio of 3 wt %, due to the change in film morphology. The performance of the solar cell is believed to be determined by the morphology and phase structure of the ternary blends as revealed by the atomic force microscopy and UV-vis spectra analysis.