Light-Induced Electric Field Assisted Self-Driven Perovskite Photodetector for Fluorescence Detection in Biomedical Application

The exceptional photo conversion efficiency of solution-processed metal halide perovskite (MHP) materials which can rarely be observed in conventional semiconductors, has led to their applications in many optoelectronic devices and sensors. Despite significant advancements in perovskite-based devices, these materials are gaining substantial attention as promising candidates for fluorescence-based sensors in biological marker detection and quantification. Herein, a self-driven CsPbBr_{<font size="1">2</font>}I-based photodetector for fluorescence detection is reported elucidating a controlled charge carrier dynamics under the light-matter interaction. The light-induced doping phenomenon, resulting from the migration of optically activated ions, generates a built-in electric field that enables device operation without external power. However, the uncontrolled migration of those ions increases the dark current and reduces the stability of the output current. To address this, we fabricate a vertically stacked FTO/PEDOT: PSS/CsPbBr₂I/PCBM/Ag photodetector with a non-symmetrical electrode design to trigger controlled ion migration upon light illumination thereby improving the device performance and output stability. The photodetector, driven by electric field due to directional light-induced polarization, achieves an ultra-low dark current (~298 pA), a high on/off ratio (~10⁵), a responsivity of 202 mA/W, a large bandwidth of 3.1 KHz, a linear dynamic range (LDR) of 81.11 dB, and a rapid response time (190 µs/100 µs) at 0 V, surpassing the performance of many similar state-of-the-art materials. These insights are valuable for practical applications, particularly in fluorescence-based biomarker detection, where the ability to detect weak signals is essential. As a proof of concept, we integrate the CsPbBr₂I-based photodetector with a microfluidic chip to detect varying concentrations of 525 nm quantum dot-conjugated beads. The device demonstrates exceptional sensitivity, with the ability to detect fluorescence signals from quantum dot solutions as low as ~22.63 nM within a microfluidic channel, highlighting its potential for future biological sensing applications.