Fabrication of bulk heterojunction organic solar cells with different configurations using electrospray

Abstract

In this work, we fabricated bulk heterojunction (BHJ) organic solar cells (OSCs) using electrospray deposition (ESD) with two different device configurations. ITO/PEDOT:PSS/P3HT: PCBM/Ca/Al and ITO/ZnO and TiO₂/P3HT: PCBM/MoO₃/Ag, termed as direct and inverted OSCs, respectively. In ZnO/ TiO₂ -based inverted solar cells, ZnO/ TiO₂ films were synthesized by sol-gel process and deposited on ITO deposited glass substrates using the spin-coating technique. P3HT/PCBM blend layers were deposited by using electrospray deposition (ESD). To observe the thermal effects on the device efficiencies, the devices were annealed at different temperatures (up to 140 °C). The cell’s performance parameters were compared at an annealing temperature of 120 °C. Comparing the performance parameters of both types of OSCs at an annealing temperature of 120 °C, the power conversion efficiency (PCE) the 1.62% is found for direct-structured OSC while 1.57% and 1.0% for ZnO/ TiO₂-based inverted structures, respectively. Interestingly, the enhanced device performance parameters were obtained with oxides-based OSCs. Compared to ZnO-based inverted OSC, the TiO₂-based inverted OSC has lower efficiency which might be due to the highly resistive surface of TiO₂ with deep-level traps. These traps can be reduced by light soaking to achieve the optimal power conversion efficiency.