Top-Illuminated Flexible Organic Photodetectors Integrated With Hole Extraction Layers Synthesized With Solution-Processed NiOₓ Films at Room Temperature

Abstract

Inverted, top-illuminated flexible organic photodetectors (OPDs) are demonstrated using solution-processed hole extraction layer (HEL) at room temperature and semitransparent electrodes. The simplified fabrication process OPD yields a low dark current density of 80.9 nA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at −5 V and a high sensitivity, as confirmed by a record high photo-to-dark-current ratio in excess of 7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> in the cases of light illuminations at 525 nm. Furthermore, the top-illuminated OPD also exhibits a high responsivity and a detection gain of 0.35A/W and 2.15 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$ </tex-math></inline-formula> 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> Jones, respectively. This flexible OPD exhibits an outstanding mechanical flexibility following tests with 60 000 bends. It is envisaged that this research will have a meaningful contribution to the next-generation OPD applications.