D-A-D or A-D-A type thiazolo[5,4-d]thiazole based π-conjugated small organic molecules and polymers have aroused a lot of interest for solution-processed organic photovoltaic materials due to their fused-ring structure, good electron accepting nature and rigid planar structure. Organic π-conjugated small molecule containing thiazolo[5,4-d]thiazole-core acceptor with furan spacer (RFTzR) was designed, synthesized and applied as electron donor material for solution-processed bulk-heterojunction (BHJ) small molecule organic solar cells (SMOSCs). The synthesized small molecule had a good thermal stability of >350 and crystalline nature also. It also has shown the self-assembly behavior due to the interconversion of liquid-crystal phases at different temperature. It has shown a good absorption band about ~473 nm in chloroform solvent suggesting a better intramolecular charge transfer (ICT) transition between thiazolo[5,4-d]thiazole-core and thiophene donor due to the rigid molecular geometry. The introduction of furan spacer improved its absorption and solubility in the common organic solvents. RFTzR exhibited good oxidation stability with HOMO and LUMO energy levels of -5.36 eV and -3.14 eV, respectively. The solution-processed organic solar cell devices of RFTzR were optimized with PCBM in different donor:acceptor blend ratios (1:1, 2:1, 3:1, w/w). The blended thin film of RFTzR:PC60BM (2:1, w/w) exhibits homogeneous and smooth morphology of low surface roughness (Rrms=1.94 nm) with nanoscale phase separation in chlorobenzene solvent.Low value of FF affects adversely on the solar cell devices which is responsible for lowering the efficiency than the expected one. The fabricated cells of RFTzR (donor) and PC60BM (acceptor) as photoactive materials showed relatively smooth thin film morphology of devices which gives a maximum PCE of 2.72% (RFTzR:PC60BM, 2:1, w/w) optimized ratio with good open-circuit voltage of 0.756 V and high photocurrent density of 10.13 mA/cm2 as compared to other devices exhibit low PECs of ~1.72% for RFTzR:PC60BM (1:1, w/w) and ~1.94% for RFTzR:PC60BM (3:1, w/w). The high FF in RFTzR:PCBM (1:1, w/w) based SMOSC is related to its low series resistance of 6.16 Ω.cm2 as compared to other SMOSCs with high series resistances of ~9.18 Ω.cm2 (RFTzR:PC60BM (2:1, w/w)) and ~11.42 Ω.cm2 (RFTzR:PC60BM (3:1, w/w)). The slight improved JSC and VOC might explain by the ultrafast and complete intermolecular charge transfer (ICT) between RFTzR and PC60BM due to the introduction of furan unit with thiazolo[5,4-d]thiazole backbone.This study makes a way for the furan bridged chromophores in small molecule organic solar cells.