In recent years, the application of magnesium oxide (MgO) in photovoltaic conductive materials has gradually evolved from an “auxiliary material” to a “key functional layer” that enhances efficiency, optimizes interfaces, and reduces costs. MgO is moving from “behind the scenes” to the “core,” becoming a critical material for next-generation high-efficiency, low-cost photovoltaic technologies.
As an Electron-Selective Contact Layer, Improving Crystalline Silicon Battery Efficiency
- Mechanism: A nanoscale magnesium oxide film is inserted into the metal/silicon interface, reducing the Schottky barrier, promoting electron tunneling, and suppressing carrier recombination.
- Measured Results: In n-type crystalline silicon batteries, the MgO/Al contact increased efficiency from <15% in traditional structures to 20%, and the process requires no high-temperature doping. In graphene/silicon Schottky junction batteries, a 1nm MgO layer boosted efficiency from 2.9% to 5.53%, reaching 8.62% after chemical doping.
As a Transparent Conductive Oxide (TCO) Replacement Material
- Advantages: Nanoscale magnesium oxide has high light transmittance (>95%) and low resistivity, which can replace traditional ITO (indium tin oxide) and solve the indium resource scarcity problem.
- Application Scenarios: As a front electrode or electron transport layer (ETL) for perovskite batteries, Oxford PV experiments show that the efficiency of MgO-based ETL perovskite batteries exceeds 25%.
Interface Passivation and Stability Enhancement
- Passivating Defects: Magnesium oxide chemically passivates silicon surface dangling bonds, reducing interface state density and extending minority carrier lifetime.
- Weather Resistance: Its high thermal stability (melting point 2852°C) and chemical inertness can protect the battery from moisture and heat degradation in outdoor environments, extending its lifespan to 25 years or more.
Low-Cost Process Compatibility
- Preparation Technologies: Magnesium oxide thin films can be realized by low-temperature sputtering, atomic layer deposition (ALD), or solution methods, compatible with existing photovoltaic production lines, eliminating the need for high-temperature diffusion processes and reducing energy consumption by more than 30%.
- Material Costs: Magnesium oxide raw materials are inexpensive (approximately 1/10 of the cost of ITO) and do not rely on rare metals, meeting the cost reduction needs of the photovoltaic industry.
Future Directions
- Perovskite/Silicon Tandem Batteries: Magnesium oxide can be used as an intermediate layer to coordinate the energy level matching of the two materials, with a target efficiency exceeding 30%.
- Flexible Photovoltaics: The mechanical flexibility of magnesium oxide thin films supports their application on flexible substrates (such as stainless steel foil), promoting wearable photovoltaic technology.