Achievement of High V_oc of 1.02 V for P3HT‐Based Organic Solar Cell Using a Benzotriazole‐Containing Non‐Fullerene Acceptor

Abstract

are mainly due to the higher LUMO of -3.74 eV (ICBA) and -3.72 eV (IC 70 BM) compared with that of PC 61 BM (-3.91 eV). However, further improvement of V oc of P3HT-based organic solar cell by modulation of fullerene is quite difficult and usually leads to the decrease the performance.On the other hand, non-fullerene acceptors have been intensively investigated and some exciting results have been obtained in recent three years, due to their adjustable absorption spectra and energy levels. [5] High PCEs of over 10% have been realized by optimizing both donor materials and nonfullerene acceptors. [6] Furthermore, to combine with classic P3HT donor polymer, electron-deficient building blocks, such as benzothiadiazole (BT), [7] diketopyrrolopyrrole (DPP), [8] perylene diimide, [9] naphthalene diimide, [10] other rylene imide, [11] and other electron-deficient building blocks [12] have been widely adopted to construct non-fullerene acceptors. The V oc and PCE of solar cells based on reported P3HT:non-fullerene small molecule acceptors are summarized in Figure 1. From Figure 1, although many kinds of non-fullerene acceptors were developed, but only five samples could realize a PCE of beyond 4% (typical value for P3HT:PCBM system). In addition, it clearly shows that the V oc could be easily improved to even beyond 1.0 V, but only one sample based on DPP segment could simultaneously achieve a V oc of higher than 1.0 V and a PCE of higher than 4%. [8e] Very recently, the highest PCE of P3HTbased solar cells reached 6.4% with a V oc of 0.8 V by using one BT-containing non-fullerene acceptor. [7f ] Thus, the development of novel non-fullerene acceptor to match well with P3HT is still urgent and necessary for the further application of P3HT-based OSCs.It is well known that benzo[d][1,2,3]triazole (BTA) has the similar chemical structure with BT and BTA-based p-type photovoltaic polymers showed ultra-high PCEs of 7.1%-8.4% and 8.2 BTA-9.5% respectively, when they are combined with fullerene derivatives [13] or non-fullerene acceptors. [14] Comparative to p-type polymers, however, BTA-containing n-type polymers show inferior PCEs of 0.18%-0.4%, [15] and there is also no report of BTA-based non-fullerene small molecule acceptors. In principle, BTA is a weaker electron-withdraw building block than BT, which could up-shift the LUMO energy levels of final materials. Furthermore, the alkyl chain in BTA could also finetune the solubility and crystallinity of final small molecules.Thus, in this communication, we adopted common A 2 A 1 DA 1 A 2 linear molecular structure to design and synthesize the first BTA-containing non-fullerene small molecule acceptor, where rhodanine (R), BTA and indacenodithiophene (IDT) were used as terminal acceptor (A 2 ), bridge acceptor (A 1 ), and central donor (D), respectively. This small molecule, named Organic solar cells (OSCs) have attracted much attention in the last two decades due to their ease of processing, mechanical flexibility, and potential for large-scale low cost fabrication. Afte...

Wide Band Gap Non‐Fullerene Small Molecular Acceptors Containing Spirobifluorene and Benzotriazole with Three Different End‐Capped Groups for P3HT‐Based Organic Solar Cells

“…[47,48] The compound 3 was afforded by coupling 1 and 2 with Pd(PPh 3 ) 4 as a catalyst. The starting materials 1 and 2 were synthesized according to our previous work and literature.…”

“…The excited wavelengths of the blend films P3HT:BTA21, P3HT:BTA23 and P3HT: BTA27 are given in Figure 5. [48] BTA21 molecule is also substituted with 3-ethylrhodanine as the terminal group, therefore, it is possible that BTA21 molecules tend to segregate together in virtue of intermolecular interaction. In the enlarged PL spectra of these thin films excited at 520 nm as shown in Figure S12, it can be easily seen that there is really difference between quenching ability of active thin films.…”

Recent Progress in Molecular Design of Fused Ring Electron Acceptors for Organic Solar Cells

“…As mentioned earlier, electron‐withdrawing π‐spacer was also inserted in FREA molecules. IDT‐2BR ( A94 , Figure ) could be considered as an analog of IDTBR with IDT core with BT‐spacer, whereas BTA1 ( A95 , Figure ) and ATT‐1 contain a benzotriazole‐ and T b T‐ester spacer, respectively. All the three FREA exhibited similar HOMO level (≈−5.5 eV), but the LUMO level was slightly elevated for BTA1 owing to weaker electron‐withdrawing nature of benzotriazole.…”

Design and synthesis of low band gap non-fullerene acceptors for organic solar cells with impressively high Jsc over 21 mA cm_2

“…Herein we utilized the thieno [3,2-b]thiphene as the central building block fused with another two thiophene units by the sp 3 carbon linked with four 4-hexylbenzene groups to improve the solubility and inhibit the molecular excessive aggregation [30][31][32]. With the above thieno [3,2-b]thiphene and thiophene fused unit as the core, three NAFs named TTIC-M, TTIC, TTIC-F were prepared with 3-(dicyanomethylidene)-indan-1-one and its two derivatives substituted with methyl or fluorine as the end groups (Fig.…”