Highly transparent Cu2O absorbing layer for thin film solar cells

Abstract

Highly transparent Cu2O thin films on transparent conducting oxide on a glass substrate were fabricated using reactive sputtering by carefully controlling the O2 flow. The impurity dependence of transmittance was thoroughly investigated, and the transmittance was found heavily depending on impurities in Cu2O thin films as confirmed by x-ray diffraction analysis. A highly transparent Cu2O thin film was fabricated using precisely impurity-controlled Cu2O thin films. The effects of impurities in a Cu2O thin film on photovoltaic properties were studied. A maximum efficiency of 8.4% was observed in the lowest-impurity Cu2O thin film.

News From Japan

“…Toshiba has continuously improved the efficiency of the Cu 2 O solar cell since its development in 2019 [2]. The efficiency reached 8.4% in December 2021 [3] and 9.5% in September 2022 [4]. It is 10.3% as of October 2023 [5].…”

Optimizing the structure and optoelectronic properties of cuprite thin films via a plasma focus device as a solar cell absorber layer

“…22 At this juncture, Toshiba Corporation has attained the pinnacle of efficiency for heterojunction cells based on Cu 2 O, clocking in at 8.4%, by utilizing Ga 2 O 3 and another intricate oxide as n-type buffer layers. 23 It is pertinent to note that these high-efficiency cells predominantly utilize n-type multicomponent oxide layers, which are deposited via techniques such as Pulsed Laser Deposition (PLD), 24 or Atomic Layer Deposition (ALD), 25 methodologies that are not yet industrially feasible for solar cell fabrication. A prominent challenge in elevating the efficiency of Cu 2 O-based solar cells resides in fabricating a structurally superior absorber layer, devoid of secondary CuO phases, utilizing a technique conducive for industrial application.…”

Al:Cu2O n-Type Semiconductors─Electrochemical Fabrication of Heterojunction and Homojunction Photovoltaic Devices

“…Other types of photovoltaic structures that satisfy such criterion have been proposed for Cu 2 O/CuO bilayer and Cu 2 O–CuO nanocomposite semiconductors . Si tandem solar cells have attracted increasing attention as a high-performance and low-cost solar cell available for conventional use, and several types of top cell materials and devices have been explored including the wide-band gap Cu 2 O semiconductor …”

“…14 Si tandem solar cells have attracted increasing attention as a high-performance and lowcost solar cell available for conventional use, 15 types of top cell materials and devices have been explored including the wide-band gap Cu 2 O semiconductor. 16 Cu 2 O is intrinsically a p-type semiconductor with a band gap energy of 2.1 eV, 17 while n-type Cu 2 O semiconductor layers can be prepared by either introducing impurity elements such as Mn and Cl into Cu 2 O layers or electrodeposition in an acidic copper(II)-acetate aqueous solution. 18,19 Two types of Cu 2 O solar cells, the heterojunction type primarily featuring an n-ZnO layer 20,21 and the homojunction type, were fabricated using various processes.…”