Synergistic (Ce/Pr/Nd)3+-doped TiO2 hetero-system as bifunctional catalyst, electrode material, and electron conveyance layer in perovskite solar cells

This work explores the synthesis and energy applications of the novel hetero-system based on (cerium/praseodymium/neodymium)-oxides doped titanium dioxide (Ce/Pr/Nd)3+-doped TiO2). With the narrow band gap energy spanning over the range of 3.62–3.89 eV, this semiconductor acquired anatase phase and average crystallite size of 77.41 nm. Rare earths triply doped TiO2 exhibited bi-functionality towards production of O2 an H2 via oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. Lowest overpotential (OER: 140 mV and HER: 135 mV) and Tafel slopes (OER: 69.1 mV dec−1 and HER: 57.2 mV dec−1) reflected the efficiency of this material for energy generation. Furthermore, Ce/Pr/Nd)3+-doped TiO2 is an excellent electrode material exhibiting electrical double layer capacitance (EDLC) with specific capacity of 749 F g−1 and a lower equivalent series resistance (Rs) of 0.12 Ω. In terms of photovoltaic applications, 16.71% efficient perovskite solar cell device containing Ce/Pr/Nd)3+-doped TiO2 as an electron transport layer was fabricated that was fully functional at the ambient conditions. The developed material possessed commendable band gap alignment with the perovskite material resulting in higher efficiency. Lanthanide doped TiO2 is an efficient, easy to prepare, sustainable, and cost effective option having potential to substitute costly energy materials.