New Electron Transport Materials for High Performance Organic Solar Cells: Synthesis and Properties of Symmetrical and Asymmetrical 1,4,5,8‐Naphthalenetetracarboxylic Dianhydride Derivatives

Abstract

Two series – symmetrical and asymmetrical – of electron‐transporting 1,4,5,8‐naphthalenetetracarboxylic dianhydride derivatives are designed and synthesized. The compounds show high thermal stability with initial destruction temperatures reaching 481 °C. The materials absorb light in UV–visible region, however, avoiding parasitic absorption that makes them suitable for the usage in high performance solar cells. Cyclic voltammetry deduces relatively high electron affinity (3.84–4.10 eV) indicating strong electron accepting nature of the molecules. The synthesized compounds have remarkable electrical properties such as high conductivity (up to 4 × 10−5 S cm−1) and electron mobility (up to 10−3 cm2 V−1 s−1). The highest solar cell efficiency is obtained for asymmetrical adduct of 1,4,5,8‐naphthalenetetracarboxylic dianhydride, pyridine‐3‐amine, and pyridin‐3,4‐diamine, and exceeds the efficiency of the reference material C60. A comparative study of the experimentally estimated and theoretically calculated by means of density functional theory method characteristics of the electron‐transporting materials is presented. The control of the symmetry of the molecular structures is responsible for the high performance of compounds in the target devices.

Naphthalene Diimide Ammonium Directed Single-Crystalline Perovskites with “Atypical” Ambipolar Charge Transport Signatures in Two-Dimensional Limit

“…According to theoretical simulation, , CBM main contribution is given by C and N orbitals of the organic cations, which is associated with the electron transfer. Namely, NDIA contributes mostly to the n-type transport, which is consistent with the previous reports. − , Overall, this atypical ambipolar behavior may be ascribed to the combination of the p-type transport of the Pb–I layer and the n-type conduction of the NDIA layer integrated by H-bonding as indicated in the crystal structure. The maximum electron mobility (μ e ) is 5.44 × 10 –3 cm 2 V –1 s –1 , and 5.83 × 10 –3 cm 2 V –1 s –1 for hole transportation (μ h ), obtained based on 10 devices (Figure S9).…”

“…20 Naphthalene diimides (NDIs) are known n-type semiconductors which have been intensively studied in organic thin film transistors (OTFTs) and have demonstrated high carrier mobilities depending on the crystalline packing. 21 Great efforts have been devoted to further improve the charge transport properties of NDIs together with the aim of understanding the structure−function relationship by means of molecular modification, 22 crystalline stacking adjustment, 23 and organic−inorganic hybridization. 24 Considering the electronic complementarity between electron-deficient NDIs and electron-rich Pb−I polyanions, 25 integrating the NDI derivatives with perovskites is highly interesting for structure engineering and photoelectric properties manipulation.…”

Perinone—New Life of an Old Molecule

“…However, in this case these rigid star-shaped perinone derivatives cannot pack efficiently, which is on the one hand advantageous to increase the solubility but at the same time decreases the density of π-stacking units in the resulting layer after processing, and thus impeding charge transport through the photoactive layer, leading to a reduced fill factor. The highest solar cell efficiency, 7.9%, was obtained for asymmetrical perinone derivative 106 [182]. The device architecture was an n-i-p type structure, based on a C60/ 2,2 -Bis(2,2-dicyanovinyl)-quinquethiophene (DCV5T)-Me:C60 hybrid planar-bulk heterojunction.…”

Efficient Flexible Organic Solar Cells with a Low-Temperature-Processed Al-Doped Zinc Oxide Electron Transport Layer

“…In I-OSCs, the selection of the electron transport layer (ETL) is critical to improve the PCE because the ETL enhances charge extraction from the BHJ layer to the metal electrode by reducing the energy barrier at the BHJ/electrode interface. − During the past years, various ETL materials have been developed, such as polyelectrolytes (PEs) (e.g., polyethylenimine (PEIE), PDINO, and PFN-Br) or metal oxides (MOs) (i.e., TiO x , SnO 2 , and ZnO). − However, an ultrathin film form (∼2 nm) of PEs is not compatible with the conventional printing method. In addition, their low electrical conductivity leads to a thickness-sensitive PCE in I-OSCs as the thickness of the PE ETL increases.…”