Modelling of advanced photovoltaic devices

为了迈向低碳的未来，避免人为气候变化的最坏影响，需要继续降低可再生能源的成本。先进的串联式光伏设备已成为提高太阳能电池板效率的关键。与传统的单结太阳能电池不同，串联式太阳能电池由多个相互堆叠的半导体层组成，每个半导体层具有不同的带隙。这使得它们能够吸收更多的阳光，从而实现更高的能效潜力。提高效率对于降低太阳能电价至关重要，因此将影响这项重要的可再生能源技术的部署。该项目的目的是开发新的模拟技术，有可能促进对串联太阳能电池器件的理解。特别是，需要新的模拟模型来克服传统的单结太阳能电池的缺点，在传统的单结太阳能电池中只评估一种半导体。该项目将把目前的建模形式扩展到串联体系结构，该体系结构可以捕捉多结太阳能电池体系结构中电荷流动和损耗的复杂性，以及钙钛矿吸收体内部的离子过程。开发串联太阳能电池的器件模型是一项复杂的任务，需要对相关的基本物理和材料有深刻的了解。这包括半导体的电学性质等信息，如带隙、载流子迁移率、载流子寿命和吸收系数。了解光如何与材料相互作用也是至关重要的。所开发的模型应该考虑入射光在串联的每一层上的吸收和反射，以及电子-空穴对(高能电荷载流子)的产生和复合。这些模型将包含器件的电气行为，包括内置电场的形成、电荷传输和产生的载流子的提取。这通常涉及到求解半导体输运方程，如漂移扩散方程或连续性方程。最重要的是，串联太阳能电池涉及多个半导体层，这些层之间的界面会显著影响器件性能。模型应考虑这些界面上的界面状态、电荷复合和带对齐。对于验证，该项目将涉及我们的项目合作伙伴(牛津物理和牛津光伏)制造的钙钛矿硅的电学和光学特性，然后可以用来为基于有限元的计算机模型的开发提供信息，以了解和优化串联太阳能电池器件。总体而言，这项工作可以影响下一代硅基光伏的发展，降低太阳能的成本。本项目属于EPSRC能源太阳能技术和光电子器件与电路研究领域。

To move to a low-carbon future and avoid the worst effects of anthropogenic climate change, continuing reductions in the cost of renewable energy are required. Advanced tandem photovoltaic devices have emerged as key to achieving improvements in the efficiency of solar panels. Unlike traditional single-junction solar cells, which have one semiconductor material to absorb light, tandem solar cells consist of multiple semiconductor layers stacked on top of each other, each with a different bandgap. This allows them to absorb a wider portion of the sunlight which enables a much higher efficiency potential. Improvements in efficiency are crucial in reducing the price of solar electricity and will thus impact the deployment of this important renewable energy technology. The aim of this project is to develop new simulation techniques with the potential to advance the understanding of tandem solar cell devices. In particular, new simulation models are required to overcome the drawbacks of conventional single-junction solar cells where only a one semiconductor is evaluated. This project will extend the current modelling formalisms to a tandem architecture that captures the complexity of charge flow and losses in multijunction solar cell architectures, as well as ionic processes inside perovskite absorbers. Developing device models for tandem solar cells is a complex task that requires a deep understanding of the underlying physics and materials involved. This includes information such as the electrical properties of the semiconductors, such as bandgap, carrier mobility, carrier lifetime, and absorption coefficients. Understanding how light interacts with the materials is also crucial. The developed models should account for the absorption and reflection of incident light at each layer of the tandem, as well as the generation and recombination of electron-hole pairs (energetic charge carriers). The models will incorporate the electrical behaviour of the device, including the formation of built-in electric fields, charge transport, and extraction of generated carriers. This often involves solving semiconductor transport equations like the drift-diffusion or continuity equations. Most importantly, the tandem solar cells involve multiple semiconductor layers, and the interfaces between these layers can significantly impact device performance. Models should account for interface states, charge recombination, and band alignment at these interfaces. For validation, this project will involve electrical and optical characterisation of perovskite-silicon manufactured by our project partners (Oxford Physics and Oxford Photovoltaics), which can then be used to inform the development of finite element-based computer models to understand and optimise tandem solar cell devices. Overall, this work can impact the development of next-generation silicon-based photovoltaics and reduce the cost of solar energy.This project falls within the EPSRC Energy Solar Technology and Optoelectronic Devices and Circuits research areas.