Zn–Cu–In–Se Quantum Dot Solar Cells with a Certified Power Conversion Efficiency of 11.6%

Abstract

The enhancement of power conversion efficiency (PCE) and the development of toxic Cd-, Pb-free quantum dots (QDs) are critical for the prosperity of QD-based solar cells. It is known that the properties (such as light harvesting range, band gap alignment, density of trap state defects, etc.) of QD light harvesters play a crucial effect on the photovoltaic performance of QD based solar cells. Herein, high quality ∼4 nm Cd-, Pb-free Zn-Cu-In-Se alloyed QDs with an absorption onset extending to ∼1000 nm were developed as effective light harvesters to construct quantum dot sensitized solar cells (QDSCs). Due to the small particle size, the developed QD sensitizer can be efficiently immobilized on TiO2 film electrode in less than 0.5 h. An average PCE of 11.66% and a certified PCE of 11.61% have been demonstrated in the QDSCs based on these Zn-Cu-In-Se QDs. The remarkably improved photovoltaic performance for Zn-Cu-In-Se QDSCs vs Cu-In-Se QDSCs (11.66% vs 9.54% in PCE) is mainly derived from the higher conduction band edge, which favors the photogenerated electron extraction and results in higher photocurrent, and the alloyed structure of Zn-Cu-In-Se QD light harvester, which benefits the suppression of charge recombination at photoanode/electrolyte interfaces and thus improves the photovoltage.

Flexible quantum dot light-emitting diodes for next-generation displays

“…[56][57][58][59][60][61][62] This issue become more significant in flexible/wearable displays, where the device is in direct contact with the human body. For instance, the European Union's Restriction of Hazardous Substances Directive regulates the use of Cd-based compounds in consumer electronics.…”

Optoelectronic Properties in Near‐Infrared Colloidal Heterostructured Pyramidal “Giant” Core/Shell Quantum Dots

“…However, due to the fast exciton recombination, it is still very challenging to fabricate devices with high photon‐to‐current (or fuel) conversion efficiency. For example, in PbS QDSCs, the fast exciton recombination limits the photon‐to‐power conversion efficiency (PCE), which is less than 12%, well below typical values of commercial silicon solar cells (in general around 20%) and its theoretical value (44% in QDSCs) 3. The synthesis of heterostructured QDs and tailoring of their composition/shape are shown to be an efficient approach to control exciton and charge carrier dynamics 4.…”

Ultrathin ALD coating on TiO2 photoanodes with enhanced quantum dot loading and charge collection in quantum dots sensitized solar cells

“…3), demonstrating that the ALD treatment is helpful for improving the conversion efficiency of the absorbed photons to electron-hole pairs. It is known that the driving force for the electron injection from QDs to the conduction band of TiO2 is determined by the Fermi level of TiO2/QDs [35]. An ultrathin coating on TiO2 mesoporous films by ALD is impossible to change the band gap structure, evident from the absorption spectral (Fig.…”