Potentiometric Titrations for Measuring the Capacitance of Colloidal Photodoped ZnO Nanocrystals

Brozek, Carl K.; Hartstein, Kimberly H.; Gamelin, Daniel R.

doi:10.1021/jacs.6b05848

Cited by 32 publications

(68 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In previous studies on Cu 2 S 13 and CdSe 9c our group has showed a strong effect of the size of the charge compensating ions on the reduction of nanocrystals. Furthermore, it has been shown by Brozek et al 25 that the charge compensating cation can affect both the injected electron stability and the chemical reduction of ZnO nanocrystals greatly. Therefore, a ZnO QD film was subsequently immersed in four different electrolyte solutions, containing different cations: lithium (Li + ), tetramethylammonium (TMA + ), tetrabutylammonium (TBA + ), and tetraoctylammonium (TOA + ).…”

Section: Results and Discussionmentioning

confidence: 99%

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

et al. 2018

View full text Add to dashboard Cite

Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li+ and Na+ the onset is at significantly less negative potentials. For larger ions (K+, quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li+ and Na+. Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies.

show abstract

Section: Results and Discussionmentioning

confidence: 99%

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The identity of the charge-compensating counteraction induces systematic shifts in the Fermi level ( E F ), having important implications on the electronic properties of the NC. 39 For example, in the case of ZnO nanocrystals, the charge storage equilibrium is mainly determined by the ethanol (EtOH) oxidation process, where two EtOH molecules accept extra holes from the NC, resulting in the formation of acetaldehyde (ZnO + ½CH 3 CH 2 OH → ZnO − + H + + ½CH 3 CHO). 14 The maximum storage in ZnO NCs is thermodynamically defined by the reverse process, in which acetaldehyde is hydrogenated, hindering the accumulation of additional electrons (ZnO − + H + + ½CH 3 CHO → ZnO + ½CH 3 CH 2 OH).…”

Section: Photodoping and Multi-charge Accumulation Of Doped Mo Ncsmentioning

confidence: 99%

“…The bilayer roughly acts as a dielectric layer in a conventional capacitor. 47–49 The charge separation is around a few angstrom 50 and implemented in the following equation for the double-layer capacitance ( C dl ): 39 with A , ε 0 , ε r , and r referring to the sphere's surface area, the permittivity of free space, the dielectric constant of the solvent, and the nanocrystal radius, respectively. This equation is the extension of the classical electrostatic capacitor ( , with d being the separation of the plates) by an additional term that accounts for the thickness t of the electrical double layer.…”

Section: Determining the Capacitance Of Photodoped Mo Ncsmentioning

confidence: 99%

“…17,39 Indeed, signatures of capacitive and pseudocapacitive charging dynamics have been reported in various MO NCs. 17,18,29,39,42 Unlike standard capacitors, supercapacitors take advantage of the double-layer electrostatic capacitance and electrochemical pseudo-capacitance, 43 resulting in high power combined with high energy storage capacity. 44,45 Electric double-layer capacitors (EDLC) operate on principles similar to those of conventional electrostatic capacitors.…”

Section: Determining the Capacitance Of Photodoped Mo Ncsmentioning

confidence: 99%

See 1 more Smart Citation

Photodoping of metal oxide nanocrystals for multi-charge accumulation and light-driven energy storage

et al. 2021

View full text Add to dashboard Cite

show abstract

“…polyoxovanadate anions,51 and semiconductor nanocrystals 61,62,[67][68][69][70]. In these systems, Lewis acidic ions, e.g., Na + , Ca 2+ , Sc 3+ , modulate redox potentials by hundreds of mV through electrostatic interactions.…”

mentioning

confidence: 99%

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

Fabrizio¹,

Lazarou²,

Payne³

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

<div> <div> <p>Titanium-based metal—organic frameworks (Ti-MOFs) attract intense research attention because they can store charges in the form of Ti3+ and they serve as photosensitizers for co-catalysts through heterogeneous photoredox reactions at the MOF-liquid interface. Both charge storage and charge transfer depend on redox potentials of the MOF and the molecular substrate, but the factors controlling these energetic aspects are not well understood. Additionally, photocatalysis involving Ti-MOFs relies on co-catalysts rather than the intrinsic Ti reactivity in part because Ti-MOFs with open metal sites are rare. Here, we report that the class of Ti-MOFs known as MUV-10 can be synthetically modified to include a range of redox-inactive ions with flexible coordination environments that control the energies of the photoactive orbitals. Lewis acidic cations installed in the MOF cluster (Cd, Sr , and Ba ) or introduced to the pores (H, Li, Na, K) tune the electronic structure and band gaps of the MOFs. Through use of optical redox indicators, we report the first direct measurement of the Fermi levels (redox potentials) of photoexcited MOFs in situ. Taken together, these results explain the ability of Ti-MOFs to store charges and provide design principles for achieving heterogeneous photoredox chemistry with electrostatic control.</p> </div> </div>

show abstract

Potentiometric Titrations for Measuring the Capacitance of Colloidal Photodoped ZnO Nanocrystals

Cited by 32 publications

References 50 publications

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

Photodoping of metal oxide nanocrystals for multi-charge accumulation and light-driven energy storage

Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites

Contact Info

Product

Resources

About