Flexible, active-matrix flat-panel image sensor for low dose X-ray detection enabled by integration of perovskite photodiode and oxide thin film transistor

Abstract

Conventional image sensor pixel is based on amorphous silicon photodiode (PD) and amorphous silicon thin film transistor (TFT), which has complex fabrication process and low frame rate due to the low mobility of amorphous silicon. Here, we demonstrate a new type of flat panel image sensor based on low-cost two-step deposited perovskite PD arrays oxide (IGZO) TFTs. Our integrated TFT/PD system takes advantage of the low off current (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-11</sup> A) of IGZO TFT and highly sensitive perovskite PD, showing a photoresponse down to 142 nW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a responsivity of 0.2 A/W, a specific detectivity of 5.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> Jones, and a high electrical switching speed (15 ms). In addition, the system can be fabricated on flexible substrates, and the perovskite PD exhibits a significant direct X-ray response, reaching a sensitivity of ~887 μCGy <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> under 9 mGy/s irradiation. Our work of combining oxide TFT with perovskite-based PD offers an advanced strategy for developing low cost and high-performance image sensors for direct and indirect X-ray imaging applications.