This review highlights our recent efforts in the development of organic semiconductors based on anthradithiophene (ADT), dithienothiophene (DTT), tetrathienoacene (TTA), benzothienodithiophene (BTDT), benzothienothiophene (BTT), chalcogen-planarized BT, and some quinoidal oligothiophenes for the application of organic thin-film transistors (OTFTs). We visualized various strategies that have been employed in molecular architecture to improve the stability as well as solubility, and the energy levels are tuned for efficient hole/electron injection, thus leading to high-performance solution processable OTFTs. The obtained mobility was correlated with the molecular stacking pattern and film morphology/microstructure of the semiconductors. Overall, this review presents information that aids reliable OTFT data analysis and provide guidelines for the development of next-generation organic semiconductors. At present, the p-type and n-type OTFTs developed by our group are able to reach the mobilities of over 4.01 and 2.5 cm2V−1 s−1, respectively. In addition, we also demonstrated the utilization of these conjugated moieties in development of high performance dye-sensitized solar cells (DSSCs) and hole transporting materials (HTM) as well as non-fullerene acceptor (NFA) for perovskite solar cells (PSCs).