Highly Twisted Dianchoring D−π–A Sensitizers for Efficient Dye-Sensitized Solar Cells

Abstract

Two new organic dyes-BPDTA and BTTA-possessing dual D-π-A units have been synthesized, characterized, and employed as efficient sensitizers for dye-sensitized solar cells. The two individual D-π-A, which are based on (E)-3-(5'-(4-(bis(4-(hexyloxy)phenyl)amino)phenyl)-[2,2'-bithiophen]-5-yl)-2-cyanoacrylic acid unit (D21L6), are connected directly between phenylene or thiophene within linear π-conjugated backbone to constitute a highly twisted architecture for suppressing the dye aggregation. The new dianchoring dyes exhibited pronounced absorption profile with higher molar extinction coefficient, which is consistent with the results obtained from density functional theory (DFT) calculations. The theoretical analysis also indicated that the charge transfer transition is mainly constituted of HOMO/HOMO-1 to LUMO/LUMO+1 that were found to be located on donor and acceptor segments, respectively. Theoretical calculations give the distance between two binding sites of 19.50 Å for BPDTA and 12.04 Å for BTTA. The proximity between two anchoring units of BTTA results in superior dye loading and, hence, higher cell efficiency. The BTTA-based device yielded an optimized efficiency of 6.86%, compared to 6.61% for the BPDTA-based device, whereas the model sensitizer D21L6 only delivered an inferior performance of 5.33% under similar conditions. Our molecular design strategy thus opens up a new horizon to establish efficient dianchoring dyes.

Electron‐Affinity‐Triggered Variations on the Optical and Electrical Properties of Dye Molecules Enabling Highly Efficient Dye‐Sensitized Solar Cells

“…One way of achieving such goal is through the development of dye molecules, which can harvest more photons while maintaining high photovoltages . In this regard, systematic studies on the structure–electrochemical property relationship are critically important . Moreover, the reported systematic studies on DSCs were mostly assembled with cobalt or iodine electrolyte, limiting the attainable open‐circuit voltage ( V OC ).…”

“…[13][14][15] In this regard, systematic studies on the structure-electrochemical property relationship are critically important. [16][17][18][19][20][21][22] Moreover, the reported systematic studies on DSCs were mostly assembled with cobalt or iodine electrolyte,l imiting the attainable open-circuit voltage (V OC ).…”

Effect of π-Conjugated Spacer in N-Alkylphenoxazine-Based Sensitizers Containing Double Anchors for Dye-Sensitized Solar Cells

“…We similarly found the substituents at the nitrogen atom of phenothiazine-cored dyes of the (D(-π-A) 2 ) (D = phenoxazine) kind have a profound effect on the cell performance [6,21,26], such as light-harvesting, dye aggregation, and dark current, and the maximum cell efficiency was compared with that of the N719-based standard cell. Hence, there are a growing number of reports on dyes with two-anchoring groups in fresh years [27][28][29][30][31][32][33]. These D(-π-A) 2 dyes show an interesting phenomenon that not only displays better light-harvesting ability but also provides efficient electron extraction compared to the congeners with only one anchor.…”

New D–π–A dyes incorporating dithieno[3,2-b:2′,3′-d]pyrrole (DTP)-based π-spacers for efficient dye-sensitized solar cells

“…The design of metal-free organic dyes can focus on molecular engineering of the electron donor, p-spacer, and acceptor for good light response, large anchoring amount and suitable energy levels. [19][20][21] Suitable molecular energy levels of organic dyes to match electrolyte are benecial to achieve an efficient regeneration of the oxidized dyes. 22 Triarylamines are mostly used as effective electron donor groups in the sensitizer molecules, which can be feasibly synthesized and modied.…”