Potential of Colloidal Quantum Dot Based Solar Cells for Near-Infrared Active Detection

Abstract

Nanocrystal-based solar cell technologies currently have two materials competing for the highest performances: PbS and perovskites. These latter benefit from a defect-tolerant electronic structure, while PbS benefits from a mature diode fabrication technique and from its near-infrared absorption. Here we choose to revisit the potential of these PbS photodiodes for near-infrared detection and more precisely for active imaging. This mode of detection combines an eye invisible source with a detector. Such detection mode is used for surveillance, industrial sorting, LIDAR, etc. Here we use a state-of-the-art photodiode geometry and we reveal its potential for near-IR active detection at 940 nm. The diode can achieve a high photoresponse of 0.5 A.W -1 , corresponding to an external quantum efficiency of 66% and a detectivity above 10 12 Jones at room temperature. The time response which is often neglected for solar cells is found to be 10 ns for rise time and 1 µs for decay time. We demonstrate that long-distance (over 150 m) and time-gated active imaging can be conducted using this device.

The complex optical index of PbS nanocrystal thin films and their use for short wave infrared sensor design

“…Here, ITO stands for tin-doped indium oxide used as a transparent conductive contact, while ETL means electron transport layer and is generally based on either ZnO 10 or TiO 2 . 11 This diode stack achieves high internal quantum efficiency that suggests optimal charge separation and band alignment. This hypothesis was further supported by later uses of this structure for LED design.…”

Time-Resolved Photoemission to Unveil Electronic Coupling between Absorbing and Transport Layers in a Quantum Dot-Based Solar Cell

“…13,14 These measurements provided a strategy to tune the carrier density in narrow band gap nanocrystals through ligand engineering. [15][16][17][18][19] From the photonic point of view, the diode structure also enables multi passes 20 of the light within the absorbing film. This also facilitates the realization of higher performance devices, with respect to planar photoconductive devices.…”

Nanocrystal Quantum Dot Devices: How the Lead Sulfide (PbS) System Teaches Us the Importance of Surfaces

“…This post-synthetic surface engineering leads to high carrier mobility (4×10 -2 cm 2 V -1 s -1 ) and improved device power conversion efficiency. 2) In 2014, Chuang et al [56] showed different ligands can be gained from the development and characterization of PbS nanocrystals and devices will facilitate their use for example in photodiode applications [164,165] or can be applied to the development of other nanocrystal chemistries for solar cells, such as leadhalide perovskites as well as non-toxic, lead-free nanocrystals such as AgBiS 2 , [166] Cu 2 S, [167] or Cu 3 BiS 3 nanocrystals. [168]…”