Controlling morphology and molecular packing of alkane substituted phthalocyanine blend bulk heterojunction solar cells

Abstract

Systematic changes in the exocyclic substiution of core phthalocyanine platform tune the absorption properties to yield commercially viable dyes that function as the primary light absorbers in organic bulk heterojunction solar cells. Blends of these complementary phthalocyanines absorb a broader portion of the solar spectrum compared to a single dye, thereby increasing solar cell performance. We correlate grazing incidence small angle x-ray scattering structural data with solar cell performance to elucidate the role of nanomorphology of active layers composed of blends of phthalocyanines and a fullerene derivative. A highly reproducible device architecture is used to assure accuracy and is relevant to films for solar windows in urban settings. We demonstrate that the number and structure of the exocyclic motifs dictate phase formation, hierarchical organization, and nanostructure, thus can be employed to tailor active layer morphology to enhance exciton dissociation and charge collection efficiencies in the photovoltaic devices. These studies reveal that disordered films make better solar cells, short alkanes increase the optical density of the active layer, and branched alkanes inhibit unproductive homogeneous molecular alignment.

Understanding and predicting the orientation of heteroleptic phosphors in organic light-emitting materials

“…Chloro-bridged bis-cyclometalated iridium complexes of the formula [Ir(C ∧ N) 2 Cl] 2 were synthesized according to literature procedures 50 . 6H- [2]benzopyrano [4,3-b]pyridin-6-one (bppo) was synthesized according to the procedure in ref. 51.…”

“…Each material was doped into a 4,4 -bis(N -carbazolyl)-1,1 -biphenyl (CBP) host matrix at 2, 6, 12 and 20% (v/v) and characterized by angle-dependent p-polarized emission (see Methods for details). Analysis of emission from films containing (bppo) 2 Listed below each structure are the angle(s) between the permanent (µ, red arrows) and transition dipole vectors (TDVs, green arrows). The dipole moment of (bppo) 2 Ir(acac) (µ = 6.18 D) lies along the molecular C 2 axis.…”

“…M olecular orientation and solid-state morphology exert a significant impact on the performance of molecular electronic devices [1][2][3][4][5] . The use of phosphorescent iridium complexes with near-unity electroluminescence quantum yields as emitters in modern organic light-emitting diodes (OLEDs) has allowed for the manufacture of devices with excellent efficiencies 6,7 .…”

Discotic liquid crystal-nanoparticle hybrid systems

“…69,70 These blends have been successfully used to fabricate solar cells that have power conversion efficiencies of up to 4.1%. Similarly, bilayer and bulk heterojunction solar cells have been prepared from liquid crystalline porphyrin donor and C 60 acceptor layers.…”

Liquid crystals in photovoltaics: a new generation of organic photovoltaics

“…Jurow et al 116 synthesized a mixture of various thioalkyl-substituted Pc derivatives 4h. Number of thioalkyl-substitution was estimated in between 3 and 10.…”