In this paper, antimony sulfide (Sb2S3) nanobars were prepared via a facile poly[N-9
′
-heptadecanyl-2,7-carbazole-alt-5,5-(4
′
,7
′
-di-2-thienyl-2
′
,1
′
,3
′
-benzothiadiazole) (PCDTBT) organic polymer-assisted hydrothermal method. The impact of PCDTBT polymer concentration on the crystal structure, shape, optical, and electrical characteristics of Sb2S3 nanobars and thin films was studied. Analysis by X-ray diffraction indicated that raising the PCDTBT concentration caused the low-crystalline structure of the Sb2S3 nanobars to transform into a polycrystalline structure. In addition, the sample had a unique Sb2S3 (orthorhombic) crystalline phase, and the crystal size increased from 32 nm to 42.6 nm. Analysis of the data revealed that the Sb2S3 nanobars had a relatively high absorption coefficient (∼105 cm−1) in the visible spectrum, with band gap values ranging from 1.71 to 1.89 eV. At a high polymer concentration, the surface morphology and grain development were enhanced, and the chemical composition analysis peaks indicate a 2 : 3 atomic ratio for Sb : S. Transmission electron microscopy (TEM) micrograph examinations demonstrate the appearance of the produced Sb2S3, which is bar-like and made of nanobars with a typical width of 200–300 nm and confirm the crystallinity of the nanobars. The optimized Sb2S3 device has a power conversion efficiency (PCE) of 5.11%, a short-circuit current density of 16.5 mA/cm2, an open-circuit voltage of 456 mV, and a fill factor of 66.62% under AM1.5G illumination. It was observed that PCDTBT has a significant role in the creation of Sb2S3 nanobars and thin films.