Scaling up organic photovoltaics (OPVs) for large-scale manufacturing requires cost-effective and efficient fabrication methods. This study investigates the application of solution-processed tungsten trioxide (WO3) nanoparticles as a hole transport layer (HTL) in inverted OPVs, specifically focusing on scalability through different deposition techniques. By exploring spin coating, slot-die coating, and spray coating, we aim to evaluate the feasibility and performance of WO3-based HTLs for large-area applications.
The increasing demand for renewable energy has driven significant research into OPVs due to their potential for low-cost, lightweight, and flexible solar cells. However, achieving high and stable power conversion efficiency (PCE) remains a challenge. Inverted OPV architectures offer advantages like simplified electrode processing and enhanced air stability. Traditional HTLs in these devices can be expensive and complex to deposit, hindering scalability. WO3 nanoparticles show promise as a solution-processable HTL alternative due to their high transparency, excellent chemical stability, and suitable work function for efficient hole extraction.
Inverted OPV devices were fabricated using the processed WO3 HTLs in conjunction with established donor and acceptor materials. Key performance metrics like PCE, current density, voltage, and fill factor were evaluated for each fabrication method. Additionally, film morphology, thickness, and surface properties were characterized using techniques like atomic force microscopy (AFM) and scanning electron microscopy (SEM).
Challenges encountered included optimizing solvent compatibility for slot-die and spray coating to achieve better film quality. Future work will focus on:
- Fine-tuning deposition parameters: Utilizing different solvent systems and processing conditions to enhance film uniformity and morphology for spray coating.
- Doping and surface modification: Exploring strategies to improve charge transport properties and stability of WO3-based HTLs.
- Large-scale device fabrication: Demonstrating the feasibility of scaled-up WO3 HTLs in roll-to-roll manufacturing processes.
Solution-processed WO3 nanoparticles show promise as scalable HTLs for inverted OPVs. While spin coating delivered the highest PCE, slot-die coating demonstrated successful performance over larger areas, highlighting its potential for large-scale manufacturing. Spray coating requires further optimization but offers the highest area coverage potential. This study paves the way for utilizing WO3 nanoparticles as a cost-effective and scalable HTL solution for achieving high-performance and commercially viable inverted OPVs.