Three novel D pi A dyes BP, BF and BT were synthesized to study the effect of heteroatoms on photovoltaic performance by introducing different electron-rich heterocyclic groups as donor to the D-pi-A system. UV-Vis absorption spectra in chloroform with concentration 2 x 10(-5) M were measured and bathochromic shift was observed in the dye BP as compared to the dyes BF and BT. Cyclic voltammetry results showed that band gap of the dyes were 1.86 eV, 1.95 eV and 1.97 eV for the dyes BP, BF and BT respectively. Photovoltaic parameters of the dyes BP, BF and BT showed open circuit voltage (V-oc) of 701, 714 and 691 mV, and short circuit current density (J(sc)) 15.73, 15.61 and 15.43 mA cm(-2), leading to sunlight to electricity power conversion efficiencies of 7.44%, 7.68% and 7.18%, respectively. It is noteworthy that, when co-adsorption with 10 mM chenodeoxycholic acid, the corresponding efficiencies of the three dyes BP, BF and BT have decreased to 6.34%, 5.63% and 5.88% respectively. These results indicating that the aggregation of the three dyes BP, BF and BT can be controlled by linking alkyl chains on the pi-spacer. Furthermore, our results provide a new method, using a planar structure of strong electron donors with heteroatoms as the donor unit, respectively conjugated to pi-spacer having alkyl chain by simple synthesis methods, which give least aggregation and ultimately gave highly efficient metal-free dyes for dye-sensitized solar cells. (C) 2018 Elsevier Ltd. All rights reserved.