Rational design of the S,N‐heteroacene‐based nonfullerene by introducing the fluorine atom for efficient high‐performance organic solar cells

Abstract

Fluorination has been established as an effective structural modification strategy to influence properties and has attracted attention in organic solar cells. Here, we design and synthesize three fused‐ring electron acceptors based on ladder‐type pentacyclic heteroacenes as the electron‐rich unit and 1,1‐dicyanomethylene‐3‐indanones with 0–2 fluorine substituents as the electron‐deficient units. Among these three molecules, two fluorine substituents nonfullerene acceptor, DTP‐2F exhibit strong absorption with high extinction coefficients and deep HOMO and LUMO level as compared with DTP‐0F and DTP‐1F. Device studies show that fluorinated nonfullerene acceptors (NFAs) lead to reduced VOC but increased JSC and FF, and therefore, the ultimate influence to efficiency depends on the compensation of VOC loss and gains of JSC and FF. Furthermore, fluorination affect to film morphology and miscibility between donor and acceptor. The fluorination of NFAs is one of the best design method of the donor and acceptor materials for efficient high‐performance organic solar cell.

Meta-Analysis of Molecular Design Strategies for Non-Fullerene Acceptor Based Organic Solar Cell Materials

“…The primary effect of halogenation can be seen through the HOMO/LUMO energies, optical band gap, maximum absorption wavelength, morphology, and charge transfer efficiencies. Many studies 44,[132][133][134][135][136][137][138][139][140][141][142][143][144][145] have found that the addition of a halogen to the ICN terminal group results in down-shifting of the HOMO and LUMO energies. This can lead to smaller energy offsets with the donor material and improves V OC .…”

“…Furthermore, halogenated NFAs can reduce the optical band gap, thus red-shifting the absorption towards the near-IR region and improving the J SC . 44,132,[134][135][136][137][138][139][141][142][143][144][145][146][147][148][149][150][151][152] Aside from the optical and energetic improvements of halogenated NFAs, halogenation can also enhance the film morphology. The high polarizability of halogens leads to reduced π-π stacking distances in NFAs 44,136,[139][140][141]144,148 , allowing for more efficient charge transfer and increasing the crystallinity of the blend film.…”

A-D-A-type electron acceptors based on pyrrole-containing ladder-type heteroarenes for organic solar cells

“…Based on a ladder-type S, N-heteropentacene consisting of four fused thiophene rings and one pyrrole ring, Tan et al developed a novel A-D-Astructured FREA with IC-2F as the end groups, named DTP-C17-4F, which showed a strong near-infrared absorption with an optical bandgap of 1.38 eV and a LUMO level of -4.16 eV. 113 When blended DTP-C17-4F with the polymer donor PM6, the optimal device demonstrated a J sc of 21.17 mA cm −2 , a V oc of 0.69 V, and a FF of 61.1%, resulting in a PCE of 8.94%. Compared to SN6IC-4F containing three fused thiophene rings and two pyrrole rings in the donor core, DTP-C17-4F exhibited a larger optical bandgap and a lower-lying LUMO level, resulting in lower J sc and V oc in corresponding OSC devices.…”

A geometric key for enhancing the radiative efficiency of ortho‐carboranyl luminophores: Indolocarbazole‐ and m‐terphenyl‐ortho‐carboranes

“…In recent times, there has been a notable upsurge in the demand for optoelectronic applications, propelling research into organic luminophores as distinguished functional materials. [1][2][3] Of particular significance is the extensive inquiry into ortho-closo-carboranes that incorporate π-conjugated organic luminophores. These materials have garnered substantial attention and have been the subject of extensive scrutiny in fields such as optoelectronics 4,5 and sensory devices 6,7 because of their exceptional thermal and chemical stabilities and unique photophysical attributes.…”

“…In recent times, there has been a notable upsurge in the demand for optoelectronic applications, propelling research into organic luminophores as distinguished functional materials 1–3 . Of particular significance is the extensive inquiry into ortho ‐ closo ‐carboranes that incorporate π‐conjugated organic luminophores.…”