Silicon Heterojunction Solar Cells Using Thermally -Evaporated Molybdenum Oxides As Dopant-Free Hole Selective Contact

Ting Yun Yang, Ling Yu Wang, Chien Chi Huang, Shih Wei Chen, Jia Min Shieh, Hsin Fei Meng, Yu Chiang Chao, Peichen Yu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review


Dopant-free carrier selective contacts have garnered significant interest for the development of high-efficiency silicon solar cells due to their low-temperature processing and suppression of free-carrier absorption. In this work, we investigate thermally-evaporated molybdenum oxides (MoOx) functioning as a hole-selective contact (HSC) for silicon heterojunction (Si HJT) solar cells. The high work function of MoOx results in upward energy band bending at the MoOx/n-type Si interface, which facilitates the hole transport and blocks the electron. We compare the optical properties of MoOx with different thickness settings of 3, 10, and 15 nm, where the optical bandgap is fitted via the tauc plot and ranging between 3.46, 3.44, and 3.42 eV, respectively. The absorption spectra of MoOx, MoOx with an intrinsic amorphous silicon (a-Si(i)) layer, and sputtered tin-doped indium oxides (ITO) are also presented. The transmission electron microscopy further reveals a 2.8nm-thick silicon oxides layer in between the MoOx and silicon interface. Preliminary results show that the Si HJT cell with a 15 nm-thick MoOx layer achieves a power conversion efficiency (PCE) of 20.3% and an open-circuit voltage (Voc) of 651.9mV, possibly limited by the pyramidal surface morphology and the a-Si(i) interface passivation layer.

Original languageEnglish
Title of host publication2021 IEEE 48th Photovoltaic Specialists Conference, PVSC 2021
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages4
ISBN (Electronic)9781665419222
StatePublished - 20 Jun 2021
Event48th IEEE Photovoltaic Specialists Conference, PVSC 2021 - Fort Lauderdale, United States
Duration: 20 Jun 202125 Jun 2021

Publication series

NameConference Record of the IEEE Photovoltaic Specialists Conference
ISSN (Print)0160-8371


Conference48th IEEE Photovoltaic Specialists Conference, PVSC 2021
Country/TerritoryUnited States
CityFort Lauderdale


  • hole selective layers
  • molybdenum oxide
  • photovoltaic cells


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