Search query: Solution-processed PbS quantum dot infrared photodetectors and photovoltaics

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abstract: In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage1. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300 1,600 nm) thermal imaging (1,500 nm and beyond) biological imaging (transparent tissue windows at 800 nm and 1,100 nm) thermal photovoltaics >1,900 nm) and solar cells (800 2,000 nm) Photoconductive polymer devices have yet to demonstrate sensitivity beyond ~800 nm (refs 2,3) Sensitizing conjugated polymers with infrared active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2 methoxy 5 (2' ethylhexyloxy p phenylenevinylene) (MEH PPV) into the infrared. We achieve, in a solution processed device and with sensitivity far beyond 800 nm, harvesting of infrared photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
author_names: Stephen A McDonald

Gerasimos Konstantatos

Shiguo Zhang

Paul W Cyr

Ethan J D Klem

Larissa Levina

Edward H Sargent
title: Solution processed PbS quantum dot infrared photodetectors and photovoltaics
venue: Nature materials
year: 2005

abstract: Colloidal quantum dots (CQDs) enable low cost, high performance optoelectronic devices including photovoltaics, photodetectors, LEDs, and lasers. Continuous wave lasing in the near infrared remains to be realized based on such materials, yet a solution processed NIR laser would be of use in communications and interconnects. In infrared quantum dots, long lived gain is hampered by a high rate of Auger recombination. Here, we report the use of perovskite shells, grown on cores of IR emitting PbS CQDs, and we thus reduce the rate of Auger recombination by up to 1 order of magnitude. We employ ultrafast transient absorption spectroscopy to isolate distinct Auger recombination phenomena and study the effect of bandstructure and passivation on Auger recombination. We corroborate the experimental findings with model based investigations of Auger recombination in various CQD core shell structures. We explain how the band alignment provided by perovskite shells comes close to the optimal required to suppress the Auger rate. These results provide a step along the path toward solution processed near infrared lasers.
author_names: Rafael Quintero-Bermudez

Randy P Sabatini

Marc Lejay

Oleksandr Voznyy

Edward H Sargent
title: Small Band Offset Perovskite Shells Increase Auger Lifetime in Quantum Dot Solids.
venue: ACS nano
year: 2017

abstract: Operating at room temperature, a solution processed photodetector with near infrared sensitivity would be a significant advancement towards industrial and scientific applications. Polymer inorganic quantum dot (QD) composites are attractive due to combination of the merits of polymeric and inorganic semiconductors in novel electronic and photonic systems. Inorganic QDs are highly suitable as infrared absorbers, and polymer bulk heterojunctions are attractive as solution processable diodes. Herein, we demonstrated a photodetector with a spectral response ranging from 300 nm to 1600 nm using a bulk heterojunction composite of a wide bandgap conjugated polymer with narrow bandgap PbS QDs. Operating at room temperature, the solution processed photodetectors exhibit a detectivity greater than 1010 cm Hz1/2 W 1 and an external quantum efficiency of over 80% in the visible region and 10% in the infrared region. All these device performances are comparable to those of their inorganic counterparts. Thus, our results demonstrate a simple way to fabricate uncooled solution processed broadband photodetectors.
author_names: Wenzhan Xu

Hui Ren Peng

Tao Zhu

Chao Yi

Lei Liu

Xiong Gong
title: A solution processed near infrared polymer: PbS quantum dot photodetectors
year: 2017

abstract: Abstract Colloidal PbS quantum dots (QDs) are promising candidates for various optoelectronic applications based on solution processed thin film techniques. In this work, a versatile layer by layer (LBL) spray deposition of the QDs is introduced aiming for a future large scale fabrication process of optoelectronic devices. As compared to spin coated QD solids, a smaller inter dot distance and a better ordered superlattice stacking behavior of the QDs are found in the spray deposited QD solids as confirmed by grazing incidence small angle X ray scattering (GISAXS) The spectral mapping combined time resolved photoluminescence analysis indicates a longer charge carrier lifetime and better order of the energy state distribution of the spray deposited QD solid comparing with the spin coated one. Thus, photodetectors based on spray deposition of QD solids demonstrate an excellent device performance, with the responsivity achieving 365.1 A/W and the detectivity reaching up to 1.4 x 1012 Jones under an illumination power of 63.5 mW/cm2 at a wavelength of 1250 nm. The spray deposited device performances indicate a great potential of spray deposition of large sized QDs in large scale fabrications for optoelectronics using longer wavelengths.
author_names: Wei-fang Chen

Wei Chen

Haodong Tang

Yulong Chen

Julian Eliah Heger

Nian Li

Lucas P Kreuzer

Yue-Min Xie

Depeng Li

Carl J Anthony

Zoe Pikramenou

Kar Wei Ng

Xiao Wei Sun

Kai Wang

Peter Muller-Buschbaum
title: Spray deposited PbS colloidal quantum dot solid for near infrared photodetectors
year: 2020

abstract: Harnessing low energy photons is of paramount importance for multi junction high efficiency solar cells as well as for thermo photovoltaic applications. However, semiconductor absorbers with the bandgap lower than 0.8 eV have been limited to III V (InGaAs) or IV (Ge) semiconductors that are characterized by high manufacturing costs and complicated lattice matching requirements in their growth and integration with higher bandgap cells. Here, we have developed solution processed low bandgap photovoltaic devices based on PbS colloidal quantum dots (CQDs) with a bandgap of 0.7 eV suited for both thermo photovoltaics and low energy solar photon harvesting. By matching the spectral response of those cells to that of the infrared solar spectrum, we report a record high short circuit current (JSC) of 37 mA cm 2 under the full solar spectrum and 5.5 mA cm 2 when placed at the back of a silicon wafer resulting in power conversion efficiencies (PCEs) of 6.4% and 0.7% respectively. Moreover, the device reached an above bandgap PCE of ~6% as a thermo photovoltaic cell recorded under a 1000 degC blackbody radiator.
author_names: Yu Bi

Arnau Bertran

Shuchi Gupta

Inigo Ramiro

Santanu Pradhan

Sotirios Christodoulou

Shanmukh Naidu Majji

Mehmet Zafer Akgul

Gerasimos Konstantatos
title: Solution processed infrared and thermo photovoltaics based on 0.7 eV bandgap PbS colloidal quantum dots.
venue: Nanoscale
year: 2019

abstract: Lead sulfide (PbS) colloidal quantum dot solar cells (CQDSCs) present the distinctive ability to utilize short wave infrared light, good ambient stability, and convenient solution based fabrication processes and thus attract much attention in the photovoltaic research field. The performance of CQDSCs has been improved by constructing the ZnO/PbS heterojunction, due to suitable band levels and electron mobility of ZnO electron transfer layer (ETL) However, the huge number of defects in low temperature processed ZnO cause an unbalanced carrier related processes, which restrict further performance enhancement and flexible production of CQDSCs. Here, we described a facile method to passivate defects in low temperature sol gel ZnO by introducing polyethylenimine (PEI) into the precursor solution. Versus the original ZnO film, the composite ZnO:PEI films exhibit better crystallization because of the Zn N interaction. A series of electronic analyses have shown that the addition of PEI reduces the work function
author_names: Lei Wang

Yuwen Jia

Yinglin Wang

Shuaipu Zang

Shengsheng Wei

Jinhuan Li

Xintong Zhang
title: Defect Passivation of Low Temperature Processed ZnO Electron Transport Layer with Polyethylenimine for PbS Quantum Dot Photovoltaics
venue: ACS Applied Energy Materials
year: 2019

abstract: Lead sulfide colloidal quantum dots (PbS CQDs) exhibit outstanding optoelectronic properties owing to their low temperature solution processability and bandgap tunability. PbS QD heterojunction detectors suffer from an incomplete interface and bulk passivation. Herein, a simple passivation method based on PbI2 was developed, which can effectively suppress the heterojunction interface and PbS QD surface defects by interface and ligand passivation. Utilizing the present strategies, PbS QD photodetectors can decrease the dark current and simultaneously increase the photocurrent. Such photodiode detectors also showed a fast response on the order of microseconds which is much faster than that of photoconductive CQD detectors (millisecond order) Also, an ultra high specific detectivity of 1013 Jones was obtained. Meanwhile, the energy conversion efficiency of PbI2 based devices reached 8% a twofold value compared to the control one. The convenient and efficient passivation method is expected to hold great potential for high performance QD optoelectronic devices.
author_names: Keke Qiao

Yulin Cao

Xiaokun Yang

J Khan

Hui Deng

Jian Zhang

Umar Farooq

Shengjie Yuan

Haisheng Song
title: Efficient interface and bulk passivation of PbS quantum dot infrared photodetectors by PbI2 incorporation
year: 2017

abstract: Abstract In this paper, we explore the impact of isopropylamine (IPAM) as a short ligand on a solution processed infrared photodetector and a photovoltaic device using lead sulfide (PbS) colloidal quantum dots. Original oleic acid capping is replaced by isopropylamine through a solution phase ligand exchange process. Then a blend of poly[2 methoxy 5 (2 ethylhexyloxy) 1,4 phenylenevinylene] or MEH PPV and the isopropylamine capped PbS colloidal quantum dots is prepared for a photosensitive layer sandwiched by two different electrodes. Results illustrate that contribution of isopropylamine can improve the responsivity of a photodetector and enhance the photovoltaic performance by increasing the open circuit voltage and short circuit current.
author_names: Taher Ghomian

Samaneh Farimand

Jin-Woo Choi
title: The effect of isopropylamine capped PbS quantum dots on infrared photodetectors and photovoltaics
year: 2017

abstract: Lead sulfide colloidal quantum dots (PbS CQDs) exhibit outstanding optoelectronic properties owing to their low temperature solution processability and bandgap tunability. PbS QD heterojunction detectors suffer from an incomplete interface and bulk passivation. Herein, a simple passivation method based on PbI2 was developed, which can effectively suppress the heterojunction interface and PbS QD surface defects by interface and ligand passivation. Utilizing the present strategies, PbS QD photodetectors can decrease the dark current and simultaneously increase the photocurrent. Such photodiode detectors also showed a fast response on the order of microseconds which is much faster than that of photoconductive CQD detectors (millisecond order) Also, an ultra high specific detectivity of 10 Jones was obtained. Meanwhile, the energy conversion efficiency of PbI2 based devices reached 8% a twofold value compared to the control one. The convenient and efficient passivation method is expected to hold great potential for high performance QD optoelectronic devices.
author_names: Keke Qiao

Yulin Cao

Xiaokun Yang

J Khan

Hui Deng

Jinshui Zhang

Umar Farooq

Shengjie Yuana

Haisheng Song
title: and bulk passivation of PbS quantum dot infrared photodetectors by PbI 2 incorporation
year: 2017

abstract: Solution processed semiconductors have opened promising avenues for next generation semiconductor and optoelectronic industries. Colloidal quantum dots (CQDs) as one of the typical materials are widely utilized for the design and development of light emission diodes, photodetectors and solar cells. Recently, an emerging process of PbS QDs ink has been employed to attain world record power conversion efficiency (PCE) by surface passivation using a PbI2 ligand to form PbI2 PbS as well as the process optimization in the field of photovoltaics. However, the bonding and debonding of the ligands on the surface of PbS QDs are dynamic reversible processes in an ink environment. The uncoordinated Pb2+ defects induced by un bonded PbS QDs serve as the recombination sites. Thus, the present ink process leaves much room for the enhancement by surface passivation of PbS QDs. Herein, we devise an efficient strategy with a supplementary phenethylammonium iodide (PEAI) ligand for the formation of the PEAI PbS interface in PbS QDs ink processed solar cells. This newly developed method can not only improve the passivation on QDs surface by iodine ions, but also simultaneously enhance the carrier collection efficiency by a graded energy alignment between PbI2 PbS and PEAI PbS layers. The corresponding power conversion efficiency (PCE) of the optimized device has significantly increased by approximately 20% more than the control device. As a result, such robust and efficient method regarded as a strategic candidate can overcome the bottleneck of imperfect passivation caused by large specific surface area and loose bonding ligands, eventually promoting industrial application of QDs.
author_names: Xiaokun Yang

Ji Yang

Muhammad Irfan Ullah

Yong Xia

Gui-jie Liang

Song Wang

Jianbing Zhang

Hsien-Yi Hsu

Haisheng Song

Jiang Tang
title: Enhanced Passivation and Carrier Collection in Ink Processed PbS Quantum Dots Solar Cells via Supplementary Ligand Strategy.
venue: ACS applied materials interfaces
year: 2020