Picolinic acid as an efficient tridentate anchoring group adsorbing at Lewis acid sites and Brønsted acid sites of the TiO₂ surface in dye-sensitized solar cells

Abstract

Picolinic acid anchored dye JA2 onto the TiO 2 via tridentate mode, the JA2+TTR2 based-device showed the highest PCE of 8.98%.We developed a novel efficient tridentate anchoring group which can anchor dye onto the TiO 2 surface via synchronously choosing Lewis acid sites and Brønsted acid sites of the TiO 2 . With the purpose of comparing the traditional carboxylate anchoring group to picolinic acid, two new D-π-A porphyrin dyes (JA1 and JA2) differing only in anchoring groups have been synthesized and applied to the dye-sensitized 10 solar cells. The picolinic acid as an anchoring group in the dye JA2 not only extended the scope of the spectral response, but also improved the charge transport properties and enhanced the electron injection efficiency. The PCE of JA1 based-device (carboxylate as the anchoring group) was 5.76%. The PCE of JA2 based-device was 7.20%, which increased by 25% compared with JA1. The dye TTR2 was used as a cosensitizer, it would not just make up for the poor absorption of porphyrin dyes in the 470-550 nm range, 15 and would suppress the main dyes aggregation and reduce the charge recombination rate. We found that picolinic acid anchor was more suitable for cosensitization system than carboxylate anchor, for there was almost no competitive adsorption between JA2 and TTR2. The JA2+TTR2 based-device showed the highest PCE of 8.98% under AM 1.5G irradiation. 65 cosensitization of zinc porphyrin dye YD2-o-C8 with organic dye Y123 greatly improved the performance of the device, showing a high PCE of 12.3% under AM 1.5G irradiation. 33 But the competitive adsorption problem has not been solved, so we need to develop a new anchoring group to solve it. Fortunately, we 70 found that the picolinic acid can be used as a promising anchoring group, which not only can anchor the dye onto the

Photoisomerization of dicyanorhodanine-functionalized thiophenes

“…10 More recently, DSSC small molecules relying on a triarylamine donor and RCN acceptor were developed [11][12][13] and have generated PCEs up to 8.98% for an optimized device using a Zn 2+ porphyrin co-sensitizer. 14 As interest in bulk-heterojunction (BHJ) devices increased, a plethora of small molecule (SM) donor materials relying on RCN appeared. 5,[15][16][17][18][19][20] A series of solution-processable SM donors were introduced, 2,21-23 each bearing terminal RCN acceptor groups along an oligothiophene backbone of varying repeat units.…”

Role of Co‐Sensitizers in Dye‐Sensitized Solar Cells

“…Zheng and co-workers reported two porphyrin dyes JA1 and JA2 by co-sensitizing with a y-shaped dye (TTR2, Figure22), which has an absorption maximum at 521 nm. [78] This report demonstrated that the IPCE action spectrum of the co-sensitized device enhanced between4 00-600nm, resulting in increased J SC of JA1 + TTR2 (13.42 mA cm À2 )a nd JA2 + TTR2 Figure 17. J-V characteristics and the corresponding IPCE spectra of devices made with LD12, CD5,and LD12 + CD5 with the same TiO 2 films (17 + 5mm) under 1sun AM 1.5 Girradiation.…”

Substituted and Anchoring Groups Improve the Efficiency of Dye-Sensitized Solar Cells

“…On the other hand, the anchoring groups of dyes can definitively influence the electron injection from the molecules into the conduction band (CB) of TiO 2 semiconductor . Recently, pyridine, 8‐hydroxylquinoline and picolinic acid have been reported as new anchoring groups in Zn‐porphyrin dyes . We have reported salicylic acids as tridentate anchoring groups for Zn‐porphyrin dyes that evidently augmented the efficiency of interfacial charge transfer .…”