Strong demand for clean, renewable sources of energy has led researchers to examine every area for alternative renewable resources. Solar energy is the only renewable source that has the potential to satisfy the world's large and increasing energy demand. The Earth receives enough solar irradiation in one hour to fulfil the world's energy needs for one year. Commercially available solar cells based on inorganic materials dominate photovoltaic (PV) technologies. However, these have drawbacks such as high production costs and environmental concerns. Therefore, organic photovoltaic cells (OPVs) have shown promising potential as they show advantages over their inorganic counterparts. These include: high absorption coefficients; better operation at lower light-intensity levels; flexible substrates; and low-cost production. Bulk heterojunction (BHJ) architecture has been frequently applied to fabricate the active layer in polymer-based solar devices. Previous studies have shown that BHJ solar cells fabricated from polymers that consist of an electron-rich donor unit and an electron-deficient acceptor monomer in an alternate donor-acceptor (D-A) arrangement result in a higher power conversion efficiency (PCE). Therefore, designing conjugated polymers that consist of alternating donor-acceptor units is a promising strategy to produce high-efficiency BHJ solar cells.