Photovoltaic effect in individual asymmetrically contacted lead sulfide nanosheets

TL;DR

This study demonstrates the photovoltaic effect in asymmetrically contacted lead sulfide nanosheets, highlighting the influence of contact metals and nanosheet thickness on device efficiency, with potential for low-cost solar cell applications.

Contribution

It reveals how contact metal work function and nanosheet height affect the photovoltaic performance of lead sulfide nanosheet devices, a novel insight for optoelectronic applications.

Findings

Mobility up to 31 cm2/Vs with palladium contacts

Photovoltaic effect observed in asymmetrically contacted nanosheets

Power conversion efficiency up to 0.94% with specific nanosheet thickness

Abstract

Solution-processable, two-dimensional semiconductors are promising optoelectronic materials which could find application in low-cost solar cells. Lead sulfide nanocrystals raised attention since the effective band gap can be adapted over a wide range by electronic confinement and observed multi-exciton generation promises higher efficiencies. We report on the influence of the contact metal work function on the properties of transistors based on individual two-dimensional lead sulfide nanosheets. Using palladium we observed mobilities of up to 31 cm2/Vs. Furthermore, we demonstrate that asymmetrically contacted nanosheets show photovoltaic effect and that the nanosheets' height has a decisive impact on the device performance. Nanosheets with a thickness 5.4 nm contacted with platinum and titanium show a power conversion efficiency of up to 0.94 % (EQE 75.70 %). The results underline the high hopes put on such materials.