Metal-free organic dyes with di(1-benzothieno)[3,2-b:2 ',3 '-d]pyrrole as an auxiliary donor for efficient dye-sensitized solar cells: Effect of the molecular engineering on the photovoltaic performance

Authors：Wu, Hanlun; Liao, Chaoqiang; Tang, Hao; Wang, Lingyun; Meier, Herbert; Cao, Derong^*

Source：Dyes and Pigments, 2019, 171: UNSP 107676.

DOI：10.1016/j.dyepig.2019.107676

• Metal-free organic dyes
• Di(1-benzothieno)[3,2-b:2 ',3 '-d]pyrrole
• Triphenylamine
• Phenothiazine
• Configuration
• Dye-sensitized solar cells

A series of novel di(1-benzothieno)[3,2-b:2',3'-d]pyrrole (DBTP)-based organic dyes (WL5-10) with D-D-pi-A or D-D-A-pi-A configurations are designed and the relationship between the properties and molecular configurations of these organic dyes are studied systematically. WL5,7-8 with D-D-pi-A configuration incorporating triphenylamine or phenothiazine as donor and DBTP as auxiliary donor and WL9-10 with D-D-A-pi-A configuration incorporating benzothiadiazole as an auxiliary acceptor are synthesized to study the effect of the molecular engineering on the photovoltaic performance. WL5,7-8 exhibit similar absorption spectra and high molar extinction coefficient. Especially, the dye WL5 with phenothiazine as terminal donor displays a high PCE of 6.75%, which is much higher than that of the dye WL1a with D-pi-A configuration. WL9-10 show the weakest performance, which is attributed to electron trap and mismatch of energy-level due to the strongest electron withdrawing group benzothiadiazole. Finally, a high power conversion efficiency of 7.94% with chenodeoxycholic acid as the co-absorbent for the DSSC based on WL5 is achieved. The results indicate that the molecular engineering of the dyes affects the photovoltaic performance greatly, and the DBTP-based organic dye with D-D-pi-A configuration by incorporating an extra terminal donor might be an effective approach to enhance the photovoltaic performance.

• Institution
  华南理工大学