Novel metal complexes for D‐(A‐π‐A) 2 motif dye sensitizer: Synthesis and photovoltaic application

Four metal complexes BDTT‐PCd, BDTT‐PZn, BDTT‐PCu, and BDTT‐PCo with the symmetrical structure were designed, synthesized, and characterized, which would be used as D‐(A‐π‐A) 2 motif dye sensitizers. These complexes adopt Cd(II), Zn(II), Cu(II), and Co(II) complexes as auxiliary electron acceptors (A), thienylbenzo[1,2‐ b :4,5‐ b ′]dithiophene (BDTT) as electron donor (D), and the 8‐quinolinol derivative as the π bridge and the acceptor (A) of D‐(A‐π‐A) 2 motif dye sensitizers. The photophysical, electrochemical, and photovoltaic properties of these complexes have been investigated. The four complexes‐based dye‐sensitized solar cells (DSSCs) device exhibited a short‐circuit photocurrent density ( J sc ) of 17.51, 17.02, 15.07, and 14.38 mA cm −2 and an attractive power conversion efficiency ( η ) of 8.82%, 8.32%, 8.03%, and 7.55%, respectively, under the AM 1.5 irradiation (100 mW cm −2 ). The photovoltaic conversion efficiency (PCE) and the short‐circuit photocurrent density ( J sc ) of BDTT‐PCd, BDTT‐PZn, BDTT‐PCu, and BDTT‐PCo are sequentially reduced; it attributed to the difference of the electron‐withdrawing ability of the auxiliary acceptor resulted by the difference of coordination abilities of metal ions Cd(II), Zn(II), Cu(II), and Co(II) with ligand. These results provide strong evidence that D‐(A‐π‐A) 2 motif complexes has great potential as promising photosensitizers in the applications of DSSCs.