Thieno[3,4‐c]pyrrole‐4,6‐dione‐Based Conjugated Polymers for Nonfullerene Organic Solar Cells

Abstract

Donor-acceptor (D-A) conjugated polymers have gotten significant attention in the past decades. Wide application area, ease of production, and cost-effectiveness have made the D-A conjugated polymers a pivotal class of organic electronics. Organic solar cells (OSCs) became one of the most critical application areas of conjugated polymers among many. Up to the last decade, intensive research has been conducted on fullerene-based OSCs. Drawbacks of fullerene derivatives like high cost, production obstacles, and difficulties in modifying molecular structure made the academia seek new alternatives. Emerging nonfullerene acceptors (NFAs) draw a new path for academia to tune OSCs' power conversion efficiency (PCE). With the ease of synthesis and purification, modification of molecular structure via various functional groups, NFAs start outperforming fullerene-based acceptors. Thieno[3,4-c]pyrrole-4,6-dione (TPD) is widely used in D-A conjugated polymers for high-performance OSCs. As a strong electron-withdrawing group, TPD provides deepened lowest unoccupied molecular orbital energy level and wide bandgaps when introduced into polymer backbones, enhancing optoelectronic properties photovoltaic performance. Herein, an overview of the applications of TPD-based donor and acceptor type conjugated polymers for nonfullerene and all-polymer solar cells in the last 5 years is provided.

Recent advances of Imide-functionalized polymer Donors for Non-fullerene Solar Cells

“…[41][42][43] Historically speaking, the creation of new imide-functionalized unit played a crucial role in the evolution of imidefunctionalized polymers. Till now, many imide building units have been created or developed, including naphthalene diimide (NDI), [44] perylene diimide (PDI), [26,45] thieno [3,4-c]pyrrole-4,6-dione (TPD), [39,46,47] phthalimide (PHI), [48,49] pyrrolo [3,4-f ] benzotriazole-5,7(6H )-dione (TzBI), [50,51] dithienophthalimide (DPI), [35,52] naphthalenothiophene imide (NTI), [22] bithiophene imide (BTI) units, [53,54] naphthodithiophene imide (NDTI), [55] thieno[3,4-f]isoindole-5,7-dione unit (TID), [25,56] 5,9-di(thiophen-2-yl)-6H -pyrrolo[3,4g ]quinoxaline-6,8(7H )-dione (PQD), [57,58] N-alkyl-4,7-di(thien-2-yl)-2,1,3-benzothiadiazole-5,6-dicarboxylic imide (DI), [59,60] pyromellitic diimide (PMDI), [61] tetraazabenzodifluoranthene diimide (BFI). [62] The chemical structure of various imide-functionalized building units are illustrated in Figure 1.…”

“…[46] In ad-dition, Various side groups can be introduced into the N-site of TPD to tune solubility of the resulting polymer and morphology of blend films. [39,46] To date, four synthetic routes have been reported for the preparation of TPD (Scheme 2) . Bjørnholm et al [74] reported the synthesis of TPD from starting materials of 3, 4-dibromothiophene, which was converted to 3, 4-dicyanothiophene by Rosenmund-von Braun reaction with cuprous cyanide (Synthetic route 1).…”

“…[78] After that, Thieno[3,4-c]pyrrole-4,6-dione (TPD) unit as an electron-deficient unit has been widely used to construct conjugated polymers for application in fullerene and non-fullerene based OSCs. [39,46], [79,80] Figure 5 summarizes the structures of typical TPD-based polymers and relevant properties are listed in Table 2. Wang et al [81] synthesized PBDT-TPD and PBDTS-TPD based on the BDT and TPD, and PCEs of 6.8 % and 7.7 % were achieved by blending with PNDI-T. Gao et al [82] synthesized polymers PBDTT-TPD and PBDT-TPD.…”

“…[34][35][36][37] 4) Last but not least, synthetic routes of most imide building units are straightforward from facile accessible materials. [38,39] These advantages make imide-functionalized polymer donors really fascinating in nonfullerene OSCs.…”

Building Block Engineering toward Realizing High-Performance Electrochromic Materials and Glucose Biosensing Platform

“…Considering π-conjugated systems, the most successful frameworks generally possess electron "push -pull" structures, achieved via the combination of electron-poor acceptor units with electron-rich donor moieties [45]. Among the electron-accepting-type frameworks, the thieno [3,4-c]pyrrole-4,6-dione (TPD) scaffold, one of the promising electron-accepting units, has several advantages, mainly providing facile synthesis, great coplanarity, a robust π-π stacking feature, and strong electron transporting, owing to the ease of switching to its quinoid form [46]. In addition to these, this unique symmetric scaffold can be modified not only with numerous functional groups from the reactive sides of the α-positions of the thiophene heterocyclic ring, but also further with N-alkylation to gain new functionalities by preserving its remarkable optoelectronic properties [47].…”