Cuprous oxide-based photocathode with enhanced nitrogen-doped back surface electric field

Abstract

The invention discloses a cuprous oxide-based photocathode with an enhanced nitrogen-doped back surface electric field, wherein the structure of the photocathode comprises conductive glass, a nitrogen-doped cuprous oxide layer, a P-type cuprous oxide light absorption layer, an N-type layer, a titanium dioxide protection layer and a cocatalyst layer from bottom to top. According to the invention, the performance of the cuprous oxide-based photocathode is greatly enhanced, so that the photocurrent of the planar cuprous oxide-based photocathode under a bias voltage of 0 V vs.RHE reaches about 10mA cm<-2> and is close to a theoretical value of 14 mA cm<-2>; and the introduction of the nitrogen-doped cuprous oxide layer can replace a traditional precious metal back electrode (gold electrode) so as to substantially reduce the preparation cost of the device, so that the cuprous oxide-based photocathode has a good development prospect, and the commercial application of the cuprous oxide-basedphotocathode is expected to be promoted.

Description

technical field [0001] The invention relates to a photocathode, in particular to a cuprous oxide-based photocathode with nitrogen-doped back surface electric field enhanced. Background technique [0002] The traditional energy crisis faced by contemporary society has promoted the development of clean and sustainable new energy. Solar energy is the most promising new energy. Using solar energy and semiconductor materials to decompose water, convert solar energy and water into clean and pollution-free hydrogen energy for storage , can solve the shortcoming of intermittent solar energy. To achieve the purpose of photoelectrocatalytic hydrogen evolution, there are specific requirements for semiconductor materials. The conduction band bottom of the semiconductor material must be negative to the redox potential of hydrogen. Cuprous oxide is an intrinsic p-type direct bandgap semiconductor material with a bandgap width of 2.1eV. The energy band position conforms to the water spli...

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Problems solved by technology

[0003] However, the work function of p-type cuprous oxide is extremely large, about 5eV. Therefore, in order to make the back electrode form an ohmic contact with cuprous oxide, the work function of the back electrode must be greater than the work function of cuprous oxide, and this condition is met. The metals used are expensive precious metals such as gold and palladium

However, ordinary conductive glass with relatively low price, such as FTO and ITO, or cheap metals such as copper, nickel, silver, etc., will form a Schottky contact with a large contact resistance when in contact with cuprous oxide. This unfavorable contact will seriously deteriorate the oxidation. Properties of Cuprous-based Photocathodes

In 2017, JL Gong's research group reported a cuprous oxide photocathode enhanced by a NiO hole transport layer. The I-V curve showed that NiO formed a good ohmic contact with cuprous oxide, but the photocurrent of the photocathode was low, only 3mA cm -2 ; the same year Michael The research group reported a cuprous oxide photocathode with a CuNiO hole transport layer, replacing the gold electrode with a CuNiO hole transport layer, so that the photocurrent of the photocathode reached 5mA cm -2 ; the photocurrent of the above device is much lower than that of cuprous oxide 14mA cm -2 Theoretical photocurrent, one of the big reasons is that the minority carrier mobility of cuprous oxide is low, and the recombination of photogenerated carriers in the body is serious.

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