Synergy Between Light Trapping and Charge Transport for Improved Collection of Photo-Current

Nickel-doped cobalt bi-metal nanoparticles (Ni/Co BMNPs) are employed in the transport buffer layer of thin-film polymer solar cell to assist in the collection of photons generated current. P3HT:PCBM blend-based polymer solar cells are successfully fabricated with modified hole transport layer (HTL)-containing BMNPs at different concentrations. The performance of the devices has generally improved compared to the reference cell by the presence of BMNPs in the transport buffer layer, and shows sign of dependence on concentration level. Significant improvements in device performance are recorded at optimum level of 0.05% BMNPs by weight, which resulted in a high current density of 15.31 mA cm⁻², and recorded 5.05% power conversion efficiency (PCE). This is 67.8% growth in PCE is compared to the reference cell. Moreover, another investigation is conducted using device simulation program to check the reproducibility of the experiments. The device that is made to mimic the best performance at 0.05% BNMP concentration produced an efficiency of 5.76%. Such reproducibility of data is an important development toward better understanding of the charge transport process in polymer solar cell. This study further provides new evidences about factors that influence device performance due to the inclusion of the BMNPs.