P‐Type Colloidal InSb Quantum Dot Ink Enables III–V Group Bulk‐Heterojunction Shortwave Infrared (SWIR) Photodetector

Abstract Infrared (IR) optoelectronics have become important owing to their various applications, such as recognition, autonomous driving, and quantum communications. In particular, detection beyond 1400‐nm wavelength in the shortwave IR (SWIR) spectrum (i.e., 1550 nm) is important for eye safety, and long‐range communication. Recently, group III–V (InAs or InSb) colloidal quantum dots (CQDs) have attracted considerable interest due to their broadband optical tunability and toxic‐elements (Pb and Hg)‐free properties. Herein, a new approach is developed to synthesize highly monodispersed InSb CQD by employing the continuous injection method, which enables facile optical bandgap tuning at a SWIR wavelength of up to 0.9 eV. Furthermore, solution ligand exchange using halides and thiolates results in effective passivation of the InSb CQD surface and renders a stable p ‐type CQD ink. Finally, bulk heterojunction (BHJ) structure is demonstrated using n ‐type InAs: p ‐type InSb CQDs, which exhibits broad absorption up to 1600 nm, and a sixfold higher responsivity compared with the pristine InSb CQD device due to the efficient charge transport in BHJ CQD solids.