Infrared Solution‐Processed Quantum Dot Solar Cells Reaching External Quantum Efficiency of 80% at 1.35 µm and Jsc in Excess of 34 mA cm−2

Bi, Yu; Pradhan, Santanu; Gupta, Shuchi; Akgül, Mehmet Zafer; Stavrinadis, Alexandros; Konstantatos, Gerasimos

doi:10.1002/adma.201704928

Cited by 99 publications

(102 citation statements)

References 42 publications

(42 reference statements)

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“…The J SC of devices based on both o ‐QDs and to ‐QDs show near unity intensity dependence ( Figure a), indicating a generation‐limited photocurrent. [ 45–46 ] The dependence of V OC on the light intensity is studied according to the relation:

V_{OC} \approx \frac{η k T}{q} In (I)

, where k is the Boltzmann constant, T is the temperature, q is the elementary charge, and η is the diode ideality factor. The values of η are estimated to be 1.32 and 1.45 for o ‐QD and to ‐QD solar cells, respectively (Figure 7b).…”

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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V_{OC} \approx \frac{η k T}{q} In (I)

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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“…Colloidal NCs have been widely investigated for use in solid thin films in numerous colloidal optoelectronic devices such as LEDs, photodetectors, solar cells, and lasers . For these applications, thermally stable NCs are highly desirable for long‐term use and commercial deployment.…”

Section: Resultsmentioning

confidence: 99%

Highly Stable, Near‐Unity Efficiency Atomically Flat Semiconductor Nanocrystals of CdSe/ZnS Hetero‐Nanoplatelets Enabled by ZnS‐Shell Hot‐Injection Growth

Altıntas

Quliyeva

Gungor

et al. 2019

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128

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Colloidal semiconductor nanoplatelets (NPLs) offer important benefits in nanocrystal optoelectronics with their unique excitonic properties. For NPLs, colloidal atomic layer deposition (c‐ALD) provides the ability to produce their core/shell heterostructures. However, as c‐ALD takes place at room temperature, this technique allows for only limited stability and low quantum yield. Here, highly stable, near‐unity efficiency CdSe/ZnS NPLs are shown using hot‐injection (HI) shell growth performed at 573 K, enabling routinely reproducible quantum yields up to 98%. These CdSe/ZnS HI‐shell hetero‐NPLs fully recover their initial photoluminescence (PL) intensity in solution after a heating cycle from 300 to 525 K under inert gas atmosphere, and their solid films exhibit 100% recovery of their initial PL intensity after a heating cycle up to 400 K under ambient atmosphere, by far outperforming the control group of c‐ALD shell‐coated CdSe/ZnS NPLs, which can sustain only 20% of their PL. In optical gain measurements, these core/HI‐shell NPLs exhibit ultralow gain thresholds reaching ≈7 µJ cm−2. Despite being annealed at 500 K, these ZnS‐HI‐shell NPLs possess low gain thresholds as small as 25 µJ cm−2. These findings indicate that the proposed 573 K HI‐shell‐grown CdSe/ZnS NPLs hold great promise for extraordinarily high performance in nanocrystal optoelectronics.

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“…However, previous Al doped ZnO (AZO) electrodes were generally produced by vacuum processing, which may limit their large‐area manufacture. Moreover, previously reported AZO films exhibit an unfavorable CB level (around 4.1 eV) limiting electron collection from the small bandgap CQD layer …”

mentioning

confidence: 99%

Activated Electron‐Transport Layers for Infrared Quantum Dot Optoelectronics

Choi

Arquer

et al. 2018

Advanced Materials

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Photovoltaic (PV) materials such as perovskites and silicon are generally unabsorptive at wavelengths longer than 1100 nm, leaving a significant portion of the IR solar spectrum unharvested. Small-bandgap colloidal quantum dots (CQDs) are a promising platform to offer tandem complementary IR PV solutions. Today, the best performing CQD PVs use zinc oxide (ZnO) as an electron-transport layer. However, these electrodes require ultraviolet (UV)-light activation to overcome the low carrier density of ZnO, precluding the realization of CQD tandem photovoltaics. Here, a new sol-gel UV-free electrode based on Al/Cl hybrid doping of ZnO (CAZO) is developed. Al heterovalent doping provides a strong n-type character while Cl surface passivation leads to a more favorable band alignment for electron extraction. CAZO CQD IR solar cell devices exhibit, at wavelengths beyond the Si bandgap, an external quantum efficiency of 73%, leading to an additional 0.92% IR power conversion efficiency without UV activation. Conventional ZnO devices, on the other hand, add fewer than 0.01 power points at these operating conditions.

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Infrared Solution‐Processed Quantum Dot Solar Cells Reaching External Quantum Efficiency of 80% at 1.35 µm and J_sc in Excess of 34 mA cm⁻²

Cited by 99 publications

References 42 publications

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

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

Highly Stable, Near‐Unity Efficiency Atomically Flat Semiconductor Nanocrystals of CdSe/ZnS Hetero‐Nanoplatelets Enabled by ZnS‐Shell Hot‐Injection Growth

Activated Electron‐Transport Layers for Infrared Quantum Dot Optoelectronics

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