Mohammed Fahmi Al Senani
Riyadh School for Boys and Girls, Riyadh, Saudi Arabia
Organic Photovoltaic (OPV) cells are important in the field of materials science due to their light weight, simple fabrication, and flexibility. Bulk-Heterojunction OPV devices contain photoactive blends of electron donor and acceptor materials between electrodes, but Electron-Selective (ES) and Hole-Selective (HS) buffer layers can be incorporated to facilitate charge-transport and increase Power Conversion Efficiencies (PCE). In this novel research, ES buffer layers and photoactive blends were optimized in Bulk-Heterojunction OPV cells fabricated onto flexible Polyethylene Terephthalate substrates. ITO was the transparent cathode, ZnO was the ES layer, P3HT:PCBM blends were the photoactive layers, MoO3 was the HS layer, and Silver was the anode. First, ZnO was optimized by introducing Al and Al nanoparticle (Al-NP) dopants. Cells utilizing ZnO:Al-NP ES layers performed better in terms of PCE (2.25%) than ZnO:Al (1.95%) and intrinsic ZnO (1.90%). Second, the thickness of ZnO:Al-NP layers was optimized, and the optimal thickness was found to be safely within the range of 7nm-45nm. Third, three photoactive blend materials (P3HT:PCBM, PBDTTT-C-T:PC70BM, and PTB7:PC70BM) were compared in cells utilizing ZnO:Al-NP layers, and PTB7:PC70BM cells demonstrated better PCEs (6.12%) than PBDTTT-C-T:PC70BM (4.10%) and P3HT:PCBM (2.25%). These findings suggest that Al-NP dopants in ZnO ES buffer layers significantly increase PCEs. Also, further modification of ZnO:Al-NP layer thicknesses was shown to be feasible in the range of 7nm-45nm. Finally, the use of PTB7:PC70BM photoactive blends was shown to greatly improve PCEs. This research highlights the potential of flexible OPV devices to provide clean, durable, low-cost, and lightweight energy sources for portable electronics.