Packing and Disorder in Substituted Fullerenes

Abstract

Fullerenes are ubiquitous as electron-acceptor and electron-transport materials in organic solar cells. Recent synthetic strategies to improve the solubility and electronic characteristics of these molecules have translated into a tremendous increase in the variety of derivatives employed in these applications. Here, we use molecular dynamics (MD) simulations to examine the impact of going from mono-adducts to bis-and tris-adducts on the structural, cohesive, and packing characteristics of [6,6]-phenyl-C 60 -butyric acid methyl ester (PCBM) and indene-C 60 . The packing configurations obtained at the MD level then serve as input for density functional theory calculations that examine the solid-state energetic disorder (distribution of site energies) as a function of chemical substitution. The variations in structural and site-energy disorders reflect the fundamental materials differences among the derivatives and impact the performance of these materials in thin-film electronic devices.

Different agglomeration properties of PC61BM and PC71BM in photovoltaic inks – a spin-echo SANS study

“…These include high-performance liquid chromatography (HPLC), 2 optical absorption, [32][33][34] uorescence spectroscopy, 32,33 static/dynamic light scattering at l > 700 nm, 18,19,22,32,33 positron lifetime spectroscopy, 20,27 electron microscopy, 22,32 small-angle neutron scattering (SANS), 14,15,[44][45][46] small-angle X-ray scattering (SAXS) 22,45,46 and theoretical calculations (molecular dynamics simulations, ab initio DFT, and others). [23][24][25][26]35,[47][48][49] Despite all these studies, the reports on the solubility and agglomeration of PC 71 BM and its comparison with PC 61 BM are still scarce 2,3 and there is in some cases a large discrepancy amongst the solubility values reported by different authors, as shown in Table 1. The most detailed comparison between the solubilities of both fullerene derivatives was performed by Kronholm et al 2 who published solubility values, determined by HPLC analysis of the liquid phase at room temperature, for PC 61 BM and PC 71 BM in different organic solvents, including chlorobenzene, toluene and chloroform.…”

Interfacing Pristine C60 onto TiO2 for Viable Flexibility in Perovskite Solar Cells by a Low‐Temperature All‐Solution Process

“…[15] In view of the high-cost synthesis and purification for fullerene derivatives, pristine fullerenes (e.g., C 60 and C 70 ) as interlayer materials have the advantage of being applied in commercial PSCs. [18] Rather than PC 61 BM, moreover, a pristine C 60 fullerene modification layer possesses better resistance to the PbI 2 solution. [18] Rather than PC 61 BM, moreover, a pristine C 60 fullerene modification layer possesses better resistance to the PbI 2 solution.…”

“…[16] In addition, pristine C 60 fullerene exhibits higher electron mobility than its derivatives (e.g., [6,6]-phenyl-C61 butyric acid methyl ester that is abbreviated as PC 61 BM), [17] owing to denser package, which facilitates intermolecular charge transport. [18] Rather than PC 61 BM, moreover, a pristine C 60 fullerene modification layer possesses better resistance to the PbI 2 solution. [19] Because I − ions were observed as the main migration species in contrast to CH 3 NH 3 + (MA + ) ions for organic-halide perovskite, [20] charge transfer from I − ions to C 60 molecules benefits I − immobilization to suppress current hysteresis and light-soaking instability.…”

Improving the Electron Mobility of ITIC by End‐Group Modulation: The Role of Fluorination and π‐Extension

“…in amorphous films are of critical importance for the formation of mesoscopic conductive networks across the bulk volume. [27,32,[45][46][47] However, accurately probing them at atomistic level still remains experimentally difficult to date. [48] Here, MD simulations were used to generate molecular packing morphologies of ITIC and its derivatives ( Figure S2, Supporting Information).…”