Influence of TiO2 nanostructures on the optical absorption of organic-inorganic perovskite

This work aims to reveal the strong influence of TiO 2 nanostructures on the light absorption property of TiO 2 and perovskite mixture. Three TiO 2 nanostructures, i.e., nanoparticles (S1), ultrapure nanorods (S2), and ultrasmall nanorods (S3), were studied: S1 was selected as a baseline; S2 and S3 were synthesized from S1 by using modified hydrothermal processes. Mesoporous TiO 2 thin films were spin-coated from solutions containing these TiO 2 nanorods and nanoparticles (S1 as baseline). Organic–inorganic hybrid perovskite CH 3 NH 3 PbI 3 was then incorporated into these mesoporous TiO 2 thin films. Optical absorption results showed that the perovskite mixture with ultrasmall TiO 2 nanostructures (S3) has significantly higher optical absorption coefficient. Finite-difference time domain models were built based on three distinct nanostructures of TiO 2 and CH 3 NH 3 PbI 3 mixtures fabricated (S1 to S3) to understand their optical absorption properties. Our work is promising to fabricate TiO 2 nanostructures, as a backbone structure, for a series of applications including photovoltaics and photodetection.