Morphological Study of Blend Thin Films of Poly(3-hexylthiophene)-block-polyisobutylene-block-poly(3-hexylthiophene):Poly(3-hexylthiophene) and Their Application to Photovoltaics

摘要

The detailed morphological studies of poly(3-hexylthiophene)(P3HT)-b-polyisobutylene(PIB)-b-P3HT:P3HT blend thin films by grazing incidence X-ray scattering (GIXS) were reported. The results of GIXS experiments indicated the formation of phase separation between P3HT and PIB domains even after blending the P3HT homopolymer below 30 wt%. The change in d-spacing values of the phase-separated under strains was suppressed by increasing the weight ratio of the P3HT homopolymer, probably due to the disruption of the microphase separation. The blending the P3HT homopolymer induced the edge-on orientation during the strain process below 75%, probably by improving the interaction between P3HT domains in the blend thin films. The OPV characteristics were obtained with the device structure of ITO/PEDOT:PSS/P3HT-b-PIB-b-P3HT:P3HT:PC61BM/Ca/Al, significantly improving the JSC and FF values by increasing the P3HT homopolymer weight ratio. The excellent elongation behavior of P3HT-b-PIB-b-P3HT:P3HT blend bulk films (P3HT < 30 wt%) could be achieved, probably due to the formation of microphase separation between semi-crystalline P3HT and rubbery PIB domains.