Low‐Noise Multispectral Photodetectors Made from All Solution‐Processed Inorganic Semiconductors

Abstract

Infrared, visible, and multispectral photodetectors are important components for sensing, security and electronics applications. Current fabrication of these devices is based on inorganic materials grown by epitaxial techniques which are not compatible with low‐cost large‐scale processing. Here, air‐stable multispectral solution‐processed inorganic double heterostructure photodetectors, using PbS quantum dots (QDs) as the photoactive layer, colloidal ZnO nanoparticles as the electron transport/hole blocking layer (ETL/HBL), and solution‐derived NiO as the hole transport/electron blocking layer (HTL/EBL) are reported. The resulting device has low dark current density of 20 nA cm‐2 with a noise equivalent power (NEP) on the order of tens of picowatts across the detection spectra and a specific detectivity (D*) value of 1.2 × 1012 cm Hz1/2 W‐1. These parameters are comparable to commercially available Si, Ge, and InGaAs photodetectors. The devices have a linear dynamic range (LDR) over 65 dB and a bandwidth over 35 kHz, which are sufficient for imaging applications. Finally, these solution‐processed inorganic devices have a long storage lifetime in air, even without encapsulation.

Unraveling the Gain Mechanism in High Performance Solution‐Processed PbS Infrared PIN Photodiodes

“…[ 17 ] In a typical reaction, 0.888 g of PbO (Sigma-Aldrich) was dissolved with 6 mmol of oleic acid in a three-necked fl ask under Ar fl ow with 50 mL of octadecene (ODE). The solution was heated and held at 130 °C.…”

“…The cross linked PbS QDs thin fi lms were fabricated with a sequential layer by layer spin casting method. Multiple PbS QDs layer was then treated with a 1,3-benzenedithiol (BDT) following the same procedure described in our previous work [ 14,17 ] to improve electronic coupling between individual nanocrystals. This treatment renders the PbS fi lm insoluble.…”

“…More recently, we reported a vertically stacked P-I-N-like photodiode with multispectral response (visible to 1300 nm) and high detectivity (>10 12 Jones) by using all solution-processed colloidal PbS QDs. [ 17 ] However, the detectivity of the IR photodiode is still lower than that of commercial InGaAs photodetectors because of their low responsivity even though they have very low noise currents. In this work, high gain and low dark current solution-processed colloidal PbS QDs IR PIN photodetectors with IR sensitivity up to 1500 nm are demonstrated.…”

Lead sulphide nanocrystal photodetector technologies

“…2f. 79,80 These devices incorporate both electron and hole blocking layers to supress charge injection from the conducting electrodes. In the case of 1, 3-benzedithiol (BDT) treated PbS NCs the Fermi level lies close to the middle of the PbS bandgap, therefore these PbS NCs are treated as an intrinsic semiconductor sandwiched between p-type and n-type materials.…”

Effect of the interface on UV–vis–IR photodetection performance of PbS/ZnO nanocomposite photocatalysts

“…Various PbS nanocomposites have been reported to enhance the photovoltaics and photodetection performance of PbS. These PbS nanocomposites include: PbS nanocomposites with organic compounds such as conjugated polymers [7], semiconducting polymer [8][9][10], poly(amidoamine) dendrimer [11], PbS nanocomposites with fullerene or fullerene derivatives [12][13][14], hybrid graphene-PbS quantum dots [15,16], PbS nanocomposites with metal nanoparticles such as Ag, Au [17][18][19], PbS quantum dots/TiO 2 heterojunction [20][21][22], PbS quantum dots/ZnO heterojunction [23][24][25][26][27]. In principle, improving e-h efficiency through the formation of PbS nanocomposites not only depends on their energy level alignment, but also depends on the interface structure of PbS nanocomposites as the migration of charger carriers occurs at the interface.…”