Interfacial Modification Using Hydrogenated TiO₂ Electron-Selective Layers for High-Efficiency and Light-Soaking-Free Organic Solar Cells

Optimizing the interfacial contacts between the photoactive layer and the electrodes is an important factor in determining the performance of organic solar cells (OSCs). A charge-selective layer with tailored electrical properties enhances the charge collection efficiency and interfacial stability. Here, the potential of hydrogenated TiO₂ nanoparticles (H-TiO₂ NPs) as an efficient electron-selective layer (ESL) material in OSCs is reported for the first time. The H-TiO₂ is synthesized by discharge plasma in liquid at atmospheric pressure, which has the benefits of a simple one-pot synthesis process, rapid and mild reaction conditions, and the capacity for mass production. The H-TiO₂ exhibits high conductivity and favorable energy level formation for efficient electron extraction, providing a basis for an efficient bilayer ESL system composed of conjugated polyelectrolyte/H-TiO₂. Thus, the enhanced charge transport and extraction efficiency with reduced recombination losses at the cathode interfacial contacts is achieved. Moreover, the OSCs composed of H-TiO₂ are almost free of light soaking, which has been reported to severely limit the performance and stability of OSCs based on conventional TiO₂ ESLs. Therefore, H-TiO₂ as a new efficient, stable, and cost-effective ESL material has the potential to open new opportunities for optoelectronic devices.