Colloidal quantum dot based solar cells: from materials to devices

Jung Hoon Song,Sohee Jeong

doi:10.1186/s40580-017-0115-0

Abstract

Colloidal quantum dots (CQDs) have attracted attention as a next-generation of photovoltaics (PVs) capable of a tunable band gap and low-cost solution process. Understanding and controlling the surface of CQDs lead to the significant development in the performance of CQD PVs. Here we review recent progress in the realization of low-cost, efficient lead chalcogenide CQD PVs based on the surface investigation of CQDs. We focus on improving the electrical properties and air stability of the CQD achieved by material approaches and growing the power conversion efficiency (PCE) of the CQD PV obtained by structural approaches. Finally, we summarize the manners to improve the PCE of CQD PVs through optical design. The various issues mentioned in this review may provide insight into the commercialization of CQD PVs in the near future.

Highlights

1 Introduction Colloidal quantum dots (CQDs) are chemically-prepared semiconductor nanocrystals, which have diameter is less than twice the Bohr radius describing the spatial extension of exciton in semiconductors
Lead chalcogenide CQDs are considered as a prominent material for a next-generation photovoltaics (PVs) [4] owing to their wide tunable bandgaps covering from visible to near-infrared wavelength regime arising from a large Bohr exciton radius and narrow bulk bandgap
The excitons in lead chalcogenide CQDs can be separated into electrons and holes because of their high dielectric constant and extinction coefficient

Summary

Introduction

Colloidal quantum dots (CQDs) are chemically-prepared semiconductor nanocrystals, which have diameter is less than twice the Bohr radius describing the spatial extension of exciton (electron–hole pair) in semiconductors. CQDs with high extinction coefficients were used instead of dyes in dyesensitized solar cells In this case, the CQD absorbs light to form excitons, and electrons and holes separated from the excitons are generally transferred through T iO2 and the electrolyte, respectively (Fig. 3a) [13]. For the PbS CQD solar cells, the excitons generated by light are separated by the internal field of the diode due to their high dielectric constant, and the separated electrons and holes move in the CQD thin film. Their electronic properties itself largely influence on the CQD solar cells. The homojunction CQD PVs show lower PCE than heterojunction ones [19]

Enhancement of power conversion efficiency through surface modification

Enhancement of power conversion efficiency using optical design

Findings

Conclusions