Graphene Doping Improved Device Performance of ZnMgO/PbS Colloidal Quantum Dot Photovoltaics

Abstract

Lead sulfi de (PbS) colloidal quantum dots (CQDs) solar cells possess the advantages of absorption into the infrared, solution processing, and multiple exciton generation, making them very competitive as a low-cost photovoltaic alternative. Employing an n-i-p ZnO/tetrabutylammonium (TBAI)-PbS/ ethanedithiol (EDT)-PbS device confi guration, the present study reports a 9.0% photovoltaic device through ZnMgO electrode engineering and graphene doping. Sol-gel-derived Zn 0.9 Mg 0.1 O buffer layer shows better transparency and higher conduction band maximum than ZnO, and incorporation of graphene and chlorinated graphene oxide into the TBAI-PbS and EDT-PbS layer respectively boosts carrier collection, leading to device with signifi cantly enhanced open circuit voltage and short-circuit current density. It is believed that incorporation of graphene into PbS CQD fi lm as proposed here, and more generally nanosheets of other materials, would potentially open a simple and powerful avenue to overcome the carrier transport bottleneck of CQD optoelectronic device, thus pushing device performance to a new level.

Enhancing Electron and Hole Extractions for Efficient PbS Quantum Dot Solar Cells

“…In the cathode side, the component and morphology of the ZnO film, the interface between the ZnO film and the PbS QDs film are all important factors. For instance, boron, nitrogen, indium, and magnesium were incorporated into the ZnO film to adjust its band gap structure and strengthen the depletion region at the ZnO/PbS interface. Nanowire array ZnO was adopted to shorten the transfer path and speed up photoelectron extraction; Modifications of the ZnO film surface using chalcogenides, conjugated polyelectrolyte, thin oxide, and CdSe quantum dot were implemented to facilitate carrier transfer from the PbS QDs to the ZnO film.…”

“…Now we will work on the anode side to improve photohole extraction. Low hole mobility (around 10 −4 cm 2 S −1 V −1 ) of the PbS‐EDT film is proved a severe problem that limits the device performance . Here we employ cuprous iodide (CuI) and EDT to co‐modify the PbS QDs (PbS‐EDT:CuI): 5 µM CuI was dissolved into the 0.02% (v/v) EDT acetonitrile solution, the mixed solution was applied on the oleic acid capped PbS CQDs for 30 s and then washed twice with acetonitrile.…”

High Performance PbS Colloidal Quantum Dot Solar Cells by Employing Solution‐Processed CdS Thin Films from a Single‐Source Precursor as the Electron Transport Layer

“…Lead chalcogenide (such as PbS or PbSe) colloidal quantum dots (CQDs) have attracted much attention in optoelectronic and photovoltaic devices, because of the remarkable advantages solution‐processing, tunable material bandgaps into the near‐infrared, and multiple exciton generation have for advanced photovoltaic cells. In particular, PbS CQD solar cells have achieved a remarkable improvement in efficiency as well as ambient stability due to rapid progress in surface passivation and beneficial modifications to the device architecture.…”

Strategies for Air‐Stable and Tunable Monolayer MoS2‐Based Hybrid Photodetectors with High Performance by Regulating the Fully Inorganic Trihalide Perovskite Nanocrystals

“…Multiple exciton generation or carrier multiplication in quantum dots is common under light illumination . Efficient exciton dissociation and charge transfer often occur at the interface of 0D/2D heterojunctions, resulting in high photocurrent signal output .…”