The Effect of Solvatochromism on the Interfacial Morphology of P3HT-CdS Nanowire Nanohybrids

Abstract

Increasing performance in organic/inorganic bulk heterojunctions hybrid photovoltaic systems hinges not only on the structure of the inorganic component but also on the morphology of the polymeric component. Changing the morphology of the organic component is a facile way of changing the morphology of the interface between the inorganic and organic components in the bulk heterojunction system. Engineering this interface to more efficiently split photogenerated excitons and transport these carriers to electrodes can increase the efficiency of photovoltaic devices. In this report, we investigate the effect of solvent quality on the morphology of the poly(3-hexylthiophene)-2,5-diyl (P3HT) polymer-semiconductor interface (solvatochromism). We have found that creating more order within the P3HT main chain in solution and prior to deposition has a profound effect on the nature of the P3HT-CdS nanowire interface. Solvents with a larger difference in solubility parameter, Δδ, relative to P3HT, such as methanol and isopropanol, create larger rod domains in the P3HT main chain and result in larger domains of crystalline P3HT at the interface. Solvents with similar solubility parameters as P3HT, such as pyridine and hexanol, create relatively shorter rod domains in the main chain and, as a result, nanohybrids with reduced crystallinity. The results of this paper further cement the importance of manipulating the rod-coil transition in the conducting polymers such as P3HT to improve the crystallinity at the polymer-semiconductor interface that can easily be scaled up to improve the efficiency of bulk heterojunction photovoltatic systems.

Surfactant Formulations for Water-Based Processing of a Polythiophene Derivative

“…The uncertainty in the persistence length was taken from the largest of the regression errors in the linear fit of each scattering pattern, the high q regime generally had a larger regression error (the fit with a slope of -1 was used for uncertainty). (Rodd, 2011). These findings indicate that the scattering objects may not be individual chains, but instead aggregated objects in solution, as expected from the Guinier plots.…”

“…As shown in Figure 5, poly(3-hexylthiophene)'s ECL is directly related to its backbone conformation and therefore dependent upon the solvent the polymer is in. Solvent interactions with orange and purple color of P3HT in CHCl 3 and pyridine, respectively (Rodd, 2011).…”

“…Intermolecular forces, especially pi-pi dispersion interactions between backbones are the driving force for such aggregation and also mediate crystal formation in the solid-state, as shown in Figure 6. Thus, the choice of (Rodd, 2011).…”

Supramolecular Assemblies of Polyoxometalate‐Tethered Diblock Copolymers with Tunable Sizes in N‐Methyl‐2‐pyrrolidone/Toluene Mixed Solvents

“…The Hildebrand solubility parameters for NMP and toluene are 23.1 and 8.9 MPa 1/2 , respectively. At the transition point (16 vol.‐% toluene), the solubility parameter of the solvent becomes 20.5 MPa 1/2 , which is comparable to the solubility parameter of the PT block (19.1 MPa 1/2 ),16 suggesting that the mixed solvent at the transition point is a good solvent for the PT block, and consequently the PT block would like to face the solvent. It is interesting to note that the morphology transition happens upon addition of identical amounts of toluene to the solutions of the three polymers.…”

A Thermochromic Superhydrophobic Surface

“…Heeger and co-workers also showed that P3HT can maintain a liquid crystalline state after crystal melting13. Similarly, such order-to-disorder transformations are observed in solvent dispersions of P3HT due to temperature or solvent type accompanied by solution color changes (solvochromic effect)141516. For instance, P3HT can form nanorods in poor solvents or when cooled in good solvents accompanied by color changes15.…”