2D-MoS2 nanosheets as effective hole transport materials for colloidal PbS quantum dot solar cells.

Srikanth Reddy Tulsani,Dattatray J Late,Arup K Rath

doi:10.1039/c8na00272j

Srikanth Reddy Tulsani, Dattatray J Late + Show 1 more

Open Access

https://doi.org/10.1039/c8na00272j

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Abstract

Herein, we demonstrate for the first time matrix-free deposition of two dimensional (2D) MoS2 nanosheets as an efficient hole transport layer (HTL) for colloidal lead sulfide (PbS) quantum dot (QD) solar cells. We have developed all-solution-processed n–p–p+ architecture solar cells where ZnO nanoparticles were used as an n-type window layer, a PbS QD layer acted as a light absorbing p-type layer and 2D-MoS2 nanosheets acted as a p+-type hole transport layer. The MoS2 nanosheets allow better interface with the PbS QD layers. The incorporation of the MoS2 hole transport layer leads to superior fill factor, higher open circuit voltage and better performance in colloidal PbS QD solar cells. These results show that one layer of MoS2 nanosheets improves the power conversion efficiency of the device from 0.92% for a hole transport material free device to 2.48%. The present work reveals the development of 2D-MoS2 nanosheets as a new hole transport layer for the fabrication of cost-effective, durable and efficient colloidal PbS quantum dot solar cells.

Highlights

IntroductionIn recent years two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted widespread attention because of their potential application in optoelectronic devices,[1] catalysis,[2] transistors,[3,4,5] photonics,[6,7,8,9] photodetectors,[10] electronics,[11] sensors,[12,13] memories,[14,15] and photocatalyzed hydrogen evolution reactions.[16,17,18] Among all TMDs, 2D MoS2 attracted signi cant interest due to its unique graphene like properties along with remarkable optoelectronic properties, like variable energy band gap, high conductivity, good exibility, high transparency, high surface area, etc
The MoS2 nanosheets synthesized by the hydrothermal method were analyzed by X-ray diffraction (XRD) to con rm their structure, phase and crystallinity
Paper shown in Fig. S2† indicate the crystalline nature of MoS2 nanosheets which supports the XRD and high-resolution transmission electron microscope (TEM) results

Summary

Introduction

In recent years two-dimensional (2D) transition metal dichalcogenides (TMDs) have attracted widespread attention because of their potential application in optoelectronic devices,[1] catalysis,[2] transistors,[3,4,5] photonics,[6,7,8,9] photodetectors,[10] electronics,[11] sensors,[12,13] memories,[14,15] and photocatalyzed hydrogen evolution reactions.[16,17,18] Among all TMDs, 2D MoS2 attracted signi cant interest due to its unique graphene like properties along with remarkable optoelectronic properties, like variable energy band gap, high conductivity, good exibility, high transparency, high surface area, etc. For the commercial viability of solar cell devices, it is of great importance to develop materials with ease of synthesis, costeffective device building and high throughput performance. This can be achieved by either further improvement in the solar cell efficiency[26,27] or reducing the cost[28,29] of the devices or both. The surface of the MoS2 nanosheets is functionalized with molecular iodine to disperse them in DMF This allows the matrix free deposition of MoS2 on top of the PbS QD layer for hole transport layer formation. MoS2 layer matches well with that of PbS QDs for efficient hole transfer, which has been exploited to improve the photovoltaic performance of solar cell devices

Experimental section

Results and discussion

Conclusions