The study was focused on evaluating the effects of different hole transport layers (HTL) on optical, morphological, and electrical properties of organic solar cell (OSC) structures. Structuring the photoactive layer with blends of poly (3-hexylthiophene) (P3HT), and [6,6] -phenyl-C61-butyric acid methyl ester (PCBM) was practiced via spin coating technique. Transition-metal-oxides of vanadium pentoxide (V2O5), tungsten trioxide (WO3), and molybdenum trioxide (MoO3) as thin films with 10 nm thick were used for the HTL layers. The deposition of all interface layers except for P3HT:PCBM photoactive layer were radio-frequency (RF) magnetron sputtered. The surface morphological and optical properties of structures produced were examined by analyzing the UV Vis NIR and atomic force microscopy (AFM) measurements. The solar cell output parameters of the inverted OSCs produced were identified depending on transition-metal-oxide (TMO) based hole-transporting materials. MoO3 HTL was exhibited as smoothest interface with a root mean square (RMS) surface roughness value of 7.11 nm. The power conversion efficiency (PCE) values of OSCs with HTL of V2O5, WO3 and MoO3 were found as 1.91%, 2.04% and 2.11%, respectively. With a comparative investigation was reported that an OSC structure with HTL of MoO3 thin film providing optimal device performance in the present study might be preferred as an alternatively effective material for opto-electronic applications.