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Surface passivation via acid vapor etching enables efficient and stable solution-processed CdTe nanocrystal solar cells

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Abstract

Achieving stable and low-resistance interfaces for hole transport layers with well-matched energy levels is crucial to maximize the performance of solution-processed CdTe nanocrystal (NC) based solar cells. Wet chemical etching with substrates immersed in dilute acid solutions is commonly adopted to modify traditional thick vacuum-evaporated CdTe layers for forming a conductive layer with good ohmic contact with the metal electrode. However, for next-generation low-cost solution-processed CdTe NC based solar cells, this method has failed so far since the acid (Br2/CH3OH or HNO3/H3PO4) can permeate easily into the grain boundaries of CdTe NCs and form a device shunt. Herein, a new technology called acid vapor etching (AVE) is developed for the first time for solution-processed CdTe NC solar cells. It's found that surface passivation can be well controlled during a mild bromine–methanol (BM) vapor etching process. Besides BM, other acid solutions such as a nitric–acetic (NA) acid solution are also suitable to adjust the CdTe interface, illustrating the remarkable universality of this method. The AVE-processed devices with an inverted configuration of ITO/ZnO/CdSe/CdTe/Au show very high efficiencies of 8.38% (BM) and 8.67% (NA) due to significant enhancement in short-circuit current, which are increased by ∼30% over that of a conventional device (5.83%) without AVE. Moreover, the AVE-processed CdTe NC solar cells show a striking improvement in stability, indicating their potential application in the manufacture of large-area solution-processed CdTe solar cells.

Graphical abstract: Surface passivation via acid vapor etching enables efficient and stable solution-processed CdTe nanocrystal solar cells

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Publication details

The article was received on 07 Oct 2019, accepted on 03 Nov 2019 and first published on 04 Nov 2019


Article type: Paper
DOI: 10.1039/C9SE00902G
Sustainable Energy Fuels, 2020, Advance Article

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    Surface passivation via acid vapor etching enables efficient and stable solution-processed CdTe nanocrystal solar cells

    X. Guo, Z. Rong, L. Wang, S. Liu, Z. Liu, K. Luo, B. Chen, D. Qin, Y. Ma, H. Wu and L. Hou, Sustainable Energy Fuels, 2020, Advance Article , DOI: 10.1039/C9SE00902G

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