Low Cost, Flexible, Perovskite BaTiO 3 Nanofibers‐Based p–n Homojunction for Multifunctional Sensing of Physical and Chemical Stimuli

Abstract In this work, a flexible, low cost, and cleanroom‐free technique to fabricate barium titanate (BaTiO 3 ) hybrid p–n homojunction‐based multifunctional sensor for photodetection, strain sensing, and chemiresistive sensing is reported. The n‐type BaTiO 3 nanofibers are synthesized using electrospinning technique and deposited on the flexible indium tin oxide (ITO) using spin‐coating method while p‐type BaTiO 3 nanoparticles are synthesized using modified sol–gel method and deposited using drop‐casting method. Detailed characterization studies are performed to reveal the formation of tetragonal phase p‐type nanoparticles and n‐type nanofibers of BaTiO 3 assembled on the ITO substrate. The fabricated hybrid junction photodetector displays an excellent external quantum efficiency of ≈3500 and photoresponsivity of ≈11 A W −1 . Further, the hybrid junction when employed as strain sensor exhibits a gauge factor of 14 and when operated in chemiresistive sensing mode can detect α1‐acid glycoprotein with an excellent sensitivity of 49.7 µ m −1 in the wide dynamic range of 0.05–10 × 10 –6 m and detection limit of 12 × 10 –9 m . Detailed studies to understand the underlying mechanism of operation for each application are done. The strategy outlined here can be further employed for sensing various physical and chemical stimuli, paving a new path for developing flexible multifunctional nanoelectronic devices.