Synergistic effect of electron transport layer and colloidal quantum dot solid enable PbSe quantum dot solar cell achieving over 10 % efficiency

Hu, Long; Geng, Xun; Singh, Simrjit; Shi, Junjie; Hu, Yicong; Li, Shaoyuan; Guan, Xinwei; He, Tengyue; Li, Xiaoning; Cheng, Zhenxiang; Patterson, Robert; Huang, Shujuan; Wu, Tom

doi:10.1016/j.nanoen.2019.103922

Cited by 45 publications

(42 citation statements)

References 40 publications

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“…Transient photocurrent (TPC) and transient photovoltage (TPV) measurements are applied to investigate the charge carrier transport and recombination rates in devices, respectively. [ 48 ] The TPC measurement shows a smaller lifetime for o ‐QD devices (Figure 7c), implying a better transport and a higher carrier collection efficiency in the o ‐QD devices. This result is in line with the GISAXS experiments that reveal the o ‐QD solids have denser particle packing behavior compared to the to ‐QD solids.…”

Section: Resultsmentioning

confidence: 99%

Facet Control for Trap‐State Suppression in Colloidal Quantum Dot Solids

Xia

Chen

Zhang

et al. 2020

Adv Funct Materials

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Trap states in colloidal quantum dot (QD) solids significantly affect the performance of QD solar cells, because they limit the open-circuit voltage and short circuit current. The {100} facets of PbS QDs are important origins of trap states due to their weak or missing passivation. However, previous investigations focused on synthesis, ligand exchange, or passivation approaches and ignored the control of {100} facets for a given dot size. Herein, trap states are suppressed from the source via facet control of PbS QDs. The {100} facets of ≈3 nm PbS QDs are minimized by tuning the balance between the growth kinetics and thermodynamics in the synthesis. The PbS QDs synthesized at a relatively low temperature with a high oversaturation follow a kinetics-dominated growth, producing nearly octahedral nanoparticles terminated mostly by {111} facets. In contrast, the PbS QDs synthesized at a relatively high temperature follow a thermodynamics-dominated growth. Thus, a spherical shape is preferred, producing truncated octahedral nanoparticles with more {100} facets. Compared to PbS QDs from thermodynamics-dominated growth, the PbS QDs with less {100} facets show fewer trap states in the QD solids, leading to a better photovoltaic device performance with a power conversion efficiency of 11.5%.

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Section: Resultsmentioning

confidence: 99%

Facet Control for Trap‐State Suppression in Colloidal Quantum Dot Solids

Xia

Chen

Zhang

et al. 2020

Adv Funct Materials

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“…Fourier transform infrared (FTIR) results show that the signal intensity of C-H modes at 2851 and 2921 cm −1 was dramatically reduced ( Figure S1, Supporting Information), indicating that the insulating OA ligands of pristine PbS CQDs were successfully replaced with the corresponding ligands in all three types of films after ligand exchange. [12,58] Transmission electron microscopy (TEM) images show that the morphology and size of PbS-PbX 2 -KI 3 CQDs have no significant change compared with PbS-PbX 2 -KI and pristine PbS-OA CQDs ( Figure S2, Supporting Information). X-ray diffraction measurements confirmed that ligand exchanged PbS CQDs retain a rock salt without impurity phase, as shown in Figure S3 in the Supporting Information, indicating that KI 3 addictive does not damage the PbS CQDs.…”

Section: Doi: 101002/advs202003138mentioning

confidence: 99%

Optimizing Surface Chemistry of PbS Colloidal Quantum Dot for Highly Efficient and Stable Solar Cells via Chemical Binding

Lei

Guan

et al. 2020

Advanced Science

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The surface chemistry of colloidal quantum dots (CQD) play a crucial role in fabricating highly efficient and stable solar cells. However, as‐synthesized PbS CQDs are significantly off‐stoichiometric and contain inhomogeneously distributed S and Pb atoms at the surface, which results in undercharged Pb atoms, dangling bonds of S atoms and uncapped sites, thus causing surface trap states. Moreover, conventional ligand exchange processes cannot efficiently eliminate these undesired atom configurations and defect sites. Here, potassium triiodide (KI3) additives are combined with conventional PbX2 matrix ligands to simultaneously eliminate the undercharged Pb species and dangling S sites via reacting with molecular I2 generated from the reversible reaction KI3 ⇌ I2 + KI. Meanwhile, high surface coverage shells on PbS CQDs are built via PbX2 and KI ligands. The implementation of KI3 additives remarkably suppresses the surface trap states and enhances the device stability due to the surface chemistry optimization. The resultant solar cells achieve the best power convention efficiency of 12.1% and retain 94% of its initial efficiency under 20 h continuous operation in air, while the control devices with KI additive deliver an efficiency of 11.0% and retains 87% of their initial efficiency under the same conditions.

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“…More importantly, the doping state of QDs must be controlled to fabricate high‐performance QD solar cells and the halide passivation of QDs must be suitable for p‐n junction design. [ 12,64,65 ] In case of Si, high doping results in a long diffusion length with improved mobility, enabling Si solar cells to have a thickness greater than hundreds micrometers. However, the diffusion length produced by QDs is currently on the order of 10 −2 cm 2 V −1 s −1 today.…”

Section: Electrical Design For Qd Pvsmentioning

confidence: 99%

Design Strategy of Quantum Dot Thin‐Film Solar Cells

Kim

Lim

Yun

et al. 2020

Small

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Quantum dots (QDs) are emerging photovoltaic materials that display exclusive characteristics that can be adjusted through modification of their size and surface chemistry. However, designing a QD‐based optoelectronic device requires specialized approaches compared with designing conventional bulk‐based solar cells. In this paper, design considerations for QD thin‐film solar cells are introduced from two different viewpoints: optics and electrics. The confined energy level of QDs contributes to the adjustment of their band alignment, enabling their absorption characteristics to be adapted to a specific device purpose. However, the materials selected for this energy adjustment can increase the light loss induced by interface reflection. Thus, management of the light path is important for optical QD solar cell design, whereas surface modification is a crucial issue for the electrical design of QD solar cells. QD thin‐film solar cell architectures are fabricated as a heterojunction today, and ligand exchange provides suitable doping states and enhanced carrier transfer for the junction. Lastly, the stability issues and methods on QD thin‐film solar cells are surveyed. Through these strategies, a QD solar cell study can provide valuable insights for future‐oriented solar cell technology.

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Synergistic effect of electron transport layer and colloidal quantum dot solid enable PbSe quantum dot solar cell achieving over 10 % efficiency

Cited by 45 publications

References 40 publications

Facet Control for Trap‐State Suppression in Colloidal Quantum Dot Solids

Facet Control for Trap‐State Suppression in Colloidal Quantum Dot Solids

Optimizing Surface Chemistry of PbS Colloidal Quantum Dot for Highly Efficient and Stable Solar Cells via Chemical Binding

Design Strategy of Quantum Dot Thin‐Film Solar Cells

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