Effective Approach for an Order-of-Magnitude-Accurate Evaluation of the Electron Mobility in Colloidal Quantum Dot Films

Francisco M Gómez-Campos,Marco Califano,Salvador Rodríguez-Bolívar

doi:10.1155/2019/5106909

Francisco M Gómez-Campos, Marco Califano + Show 1 more

Open Access

https://doi.org/10.1155/2019/5106909

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Abstract

Being able to estimate the electron mobility of colloidal quantum dot films is of great importance for determining their suitability to specific applications and would lead to huge savings in terms of time and resources that may otherwise be wasted trying to build and optimize a device whose transport characteristics can be predicted to be poor from the outset. This task is however complicated by the complexity of the system and the large number of parameters that can potentially affect the final result. Here, we derive a simple, fitting-parameter-free, order-of-magnitude-accurate expression to estimate the dark mobility of such 2D structures and validate it by applying it to real systems and comparing its predictions with those of other recently proposed approaches and with available experimental data. The results quantify the superiority of our expression to estimate mobilities in colloidal quantum dot films.

Highlights

The use of semiconductor colloidal quantum dots (CQDs) as building blocks for optoelectronic and energy-harvesting devices has become widespread [1,2,3,4,5]
A simple expression for estimating the maximum dark mobility in 3D CQD supercrystals, obtained within the k·p framework under the assumption that fluctuations in the size of the CQDs represent the main source of electron scattering, was proposed recently by Shabaev et al [9]
We introduce a small perturbation by replacing one of the single quantum dot potentials with that of a smaller quantum dot

Summary

Introduction

The use of semiconductor colloidal quantum dots (CQDs) as building blocks for optoelectronic and energy-harvesting devices has become widespread [1,2,3,4,5] Such applications usually require these nanostructures to be arrayed in 2D or 3D supercrystals, whose optical properties retain similar characteristics (i.e., optical gap) to their constituents. The transport properties of these arrays, on the other hand, cannot be as inferred from those of the single dots in solution In this respect, the evaluation of the film mobility is of particular interest, as its magnitude determines the range of applications the material would be better suited for [1, 2, 6,7,8]. For arrays of CdSe and PbSe CQDs, our predicted mobilities are consistent with those observed experimentally in these systems [7, 10], whereas the mobility values obtained using the expression from Ref. [9] are at least one order of magnitude smaller than our estimates and over a factor of 20 smaller than the experiment

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Conclusion