The effect of water on colloidal quantum dot solar cells

Guozheng Shi,Haibin Wang,Yannan Zhang,Botong Chen,Liang Zhang,Shiyun Xiong,Qing Shen,Yaohong Zhang,Takashi Sagawa,Xing Meng,Steffen Duhm,Takaya Kubo,Tianyu Zhai ,Yifan Chen,Lu Wang,Xufeng Ling,Chen Cheng,Xinnan Mao,Zeke Liu,Tao Li,Ryota Jono,Xinyi Liu,Hiroshi Segawa,Xuliang Zhang,Yang Liu,Wanli Ma

doi:10.1038/s41467-021-24614-7

Abstract

Almost all surfaces sensitive to the ambient environment are covered by water, whereas the impacts of water on surface-dominated colloidal quantum dot (CQD) semiconductor electronics have rarely been explored. Here, strongly hydrogen-bonded water on hydroxylated lead sulfide (PbS) CQD is identified. The water could pilot the thermally induced evolution of surface chemical environment, which significantly influences the nanostructures, carrier dynamics, and trap behaviors in CQD solar cells. The aggravation of surface hydroxylation and water adsorption triggers epitaxial CQD fusion during device fabrication under humid ambient, giving rise to the inter-band traps and deficiency in solar cells. To address this problem, meniscus-guided-coating technique is introduced to achieve dense-packed CQD solids and extrude ambient water, improving device performance and thermal stability. Our works not only elucidate the water involved PbS CQD surface chemistry, but may also achieve a comprehensive understanding of the impact of ambient water on CQD based electronics.

Highlights

Almost all surfaces sensitive to the ambient environment are covered by water, whereas the impacts of water on surface-dominated colloidal quantum dot (CQD) semiconductor electronics have rarely been explored
The results indicate that the adsorbed water could govern the temperature-dependent change of CQD surface chemistry through water desorption, hydroxylation, and dehydration process
In summary, we identified that the hydroxylated PbS CQD surfaces are covered by H-bonded water, which governs the temperature-dependent evolution of the surface chemical environment and generates significant effects on CQD nanostructure morphology, optoelectronic properties, as well as final photovoltaic performance

Summary

Introduction

Almost all surfaces sensitive to the ambient environment are covered by water, whereas the impacts of water on surface-dominated colloidal quantum dot (CQD) semiconductor electronics have rarely been explored. The aggravation of surface hydroxylation and water adsorption triggers epitaxial CQD fusion during device fabrication under humid ambient, giving rise to the inter-band traps and deficiency in solar cells. To address this problem, meniscus-guided-coating technique is introduced to achieve dense-packed CQD solids and extrude ambient water, improving device performance and thermal stability. This feature of CQD with controllable surface geometries provides a model platform for the study of the water effect on CQD characteristics, starting from the atom-level surface chemistry to the macroscopic photovoltaic properties

Methods

Results

Conclusion