Thieno[3,2‐b][1]benzothiophene Derivative as a New π‐Bridge Unit in D–π–A Structural Organic Sensitizers with Over 10.47% Efficiency for Dye‐Sensitized Solar Cells

Abstract

Three new thieno[3,2‐b][1]benzothiophene (TBT)‐based donor–π–acceptor (D–π–A) sensitizers, coded as SGT‐121, SGT‐129, and SGT‐130, have been designed and synthesized for dye‐sensitized solar cells (DSSCs), for the first time. The TBT, prepared by fusing thiophene unit with the phenyl unit of triphenylamine donor, is utilized as the π‐bridge for all sensitizers with good planarity. They have been molecularly engineered to regulate the highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) energy levels and extend absorption range as well as to control the electron‐transfer process that can ensure efficient dye regeneration and prevent undesired electron recombination. The photovoltaic performance of SGT‐sensitizer‐based DSSCs employing Co(bpy)32+/3+ (bpy = 2,2′‐bipyridine) redox couple is systematically evaluated in a thorough comparison with Y123 as a reference sensitizer. Among them, SGT‐130 with benzothiadiazole‐phenyl (BTD‐P) unit as an auxiliary acceptor exhibits the highest power‐conversion efficiency (PCE) of 10.47% with Jsc = 16.77 mA cm−2, Voc = 851 mV, and FF = 73.34%, whose PCE is much higher than that of Y123 (9.5%). It is demonstrated that the molecular combination of each fragment in D–π–A organic sensitizers can be a pivotal factor for achieving the higher PCEs and an innovative strategy for strengthening the drawbacks of the π‐bridge.

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

“…[6][7][8][9][10][11][12] Highefficiency low-cost DSCs are required to be able to commercialize this technology.O ne way of achieving such goal is through the development of dye molecules,which can harvest more photons while maintaining high photovoltages. [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 ).…”

Electron‐Withdrawing Anchor Group of Sensitizer for Dye‐Sensitized Solar Cells, Cyanoacrylic Acid, or Benzoic Acid?

“…The order of the electron lifetime was in line with the V oc values of ZL005 (808 mV) and ZL003 (957 mV). The highest electron lifetime ( τ hr = 1/ω min = 2πƒ max ) was calculated from the midfrequency region of the Bode plots (Figure b), and it was obvious that the value of τ hr for ZL003 was greater than that of ZL005; hence, the ZL003‐based DSSC had longer electron lifetime, which indicated that ZL003 has more effective suppression of back reaction of injected electrons from Co 3+ ions. Therefore, it is reasonable to conclude that ZL003 gives a higher V oc compared with ZL005, which yields a higher device efficiency.…”

“…The average lifetime of ZL003 absorbed onto Al 2 O 3 films and TiO 2 films was 5.15 and 0.51 ns, respectively, whereas the average lifetime of ZL005 was 4.67 ns on Al 2 O 3 films and 0.85 ns on TiO 2 films. From the comparison of the PL decays for TiO 2 and Al 2 O 3 samples, we estimated the electron injection efficiencies of the dyes using Equation …”

Solvent-Acidity-Driven Change in Photophysics and Significant Efficiency Improvement in Dye-Sensitized Solar Cells of a Benzothiazole-Derived Organic Sensitizer

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Typically, organic sensitizers consist of an electron donating group, a π-conjugated bridge and an electron accepting unit. [19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] In addition, an anchoring group (usually comprising a carboxylic acid moiety, COOH) is introduced, that allows the chemical adsorption of the dye on the metal-oxide semiconductor.…”