Designs and understanding of small molecule-based non-fullerene acceptors for realizing commercially viable organic photovoltaics

Abstract

Organic photovoltaics (OPVs) have emerged as a promising next-generation technology with great potential for portable, wearable, and transparent photovoltaic applications. Over the past few decades, remarkable advances have been made...

Binding Energy of Triplet Excitons in Nonfullerene Acceptors: The Effects of Fluorination and Chlorination

“…In addition, the reduction of ΔE ST enhances the intersystem crossing (ISC) from S 1 to T 1 , which favors the generation of T 1 excitons. 35 Some of these characteristics of triplet and singlet excitons were experimentally observed in oligoacenes by Hummer et al 42 and theoretically reproduced with good precision by Hu et al 43 In the latter study, the calculations were performed combining a polarizable continuum model (PCM) and an optimally tuned range-separated (RS) hybrid functional. From a theoretical perspective, the great importance of considering solid-state polarization effects for the stabilization of singlet and triplet energies was stressed by Chen and coauthors.…”

“…Importantly, when the energy gap between T 1 and S 1 decreases, Δ E ST = E S1 – E T1 , the exciton binding energy of the triplet exciton ( E b,T ) approaches the binding energy of the singlet exciton ( E b,S ), which would help the dissociation of the triplet excitons. In addition, the reduction of Δ E ST enhances the intersystem crossing (ISC) from S 1 to T 1 , which favors the generation of T 1 excitons . Some of these characteristics of triplet and singlet excitons were experimentally observed in oligoacenes by Hummer et al and theoretically reproduced with good precision by Hu et al In the latter study, the calculations were performed combining a polarizable continuum model (PCM) and an optimally tuned range-separated (RS) hybrid functional.…”

“…Among them, we can highlight the use of the two types of excited states, i.e. , singlets (S 1 , ..., S n ) and triplets (T 1 , ..., T n ), in the photovoltaic process. − …”

Simple Tricyclic-Based A-π-D-π-A-Type Nonfullerene Acceptors for High-Efficiency Organic Solar Cells

“…Recently, acceptor–donor–acceptor (A–D–A)-type fused-ring electron acceptors (FREAs) have subverted the predominant position of classical fullerene-based acceptors and have led organic solar cells (OSCs) to a new era. − The power conversion efficiencies (PCEs) of FREAs have been boosted to 19%, which endows a great potential for the commercialization of OSCs in the near future. , FREAs are generally composed of an electron-rich polycyclic fused-ring core, bulky side chains, and two electron-deficient terminal groups . The fused-ring core has a crucial impact on the photovoltaic properties.…”

Facile synthesis of annulated benzothiadiazole derivatives and their application as medium band gap acceptors in organic photovoltaic devices

“…In A-D-A materials, the energetics can be tuned by appropriate choice of the D and A components, with the molecular HOMO (highest occupied molecular orbital) largely determined by the electron rich D, and the LUMO (lowest unoccupied molecular orbital) by the acceptor, A. 9,10 Thus, the nature of A plays an important role in material performance in many applications.…”