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Carrier lifetime measurement at grain boundaries in thin-film solar cells

薄膜太阳能电池晶界处的载流子寿命测量

基本信息

批准号：
EP/K001620/1
负责人：
Budhika Mendis
金额：
$ 3.24万
依托单位：
Durham University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=EP%2FK001620%2F1
关键词：
Carrier lifetime measurement grain boundaries

项目摘要

The total solar energy reaching the Earth in less than an hour is greater than the annual global energy demand. Solar cells provide valuable renewable energy by converting sunlight into electricity. Silicon currently dominates solar cell technology, although it is an intrinsically poor absorber of light. On the other hand thin-film solar cells utilise strongly absorbing materials so that the material volume is reduced to a thin layer a few micrometers in thickness, thereby lowering cost. Examples include CdTe and CIGS, the former being commercially produced with an annual output exceeding 1 Giga Watt.A common feature of thin-film solar cells is the high density of crystal defects known as 'grain boundaries'. A grain boundary demarcates the region where two crystals (i.e. grains) of different orientation impinge on one another. They typically reduce the overall solar cell efficiency and need to be passivated for optimum device operation. Indeed in CdTe solar cells a 'chlorine activation' step is used post-deposition where the device is annealed in a chlorine-rich environment leading to a ten-fold improvement in efficiency. It is thought that chlorine segregates to the grain boundaries thereby passivating them, although the precise mechanism is unknown.In this project we will use state-of-the-art measurements of carrier lifetimes at individual grain boundaries to explore the fundamental mechanism(s) behind chlorine activation. The carrier lifetime is an important parameter specifying the electrical activity of a given grain boundary and its effect on device operation. In order to carry out such measurements a high spatial resolution (few nanometres) must be combined with excellent temporal resolution (a few picoseconds) the technical demands for which have only recently been overcome. We will carry out the very first measurements of grain boundary carrier lifetimes in CdTe thin-film solar cells using the new Attolight scanning electron microscope recently installed at EPFL, Switzerland. This is the only scientific instrument of its kind in the world capable of carrying out such analyses. We will also explore the relative effectiveness of different chlorine activation routes (i.e. standard activation using solid CdCl2 and gas activation methods) for passivating grain boundaries. This has important long term commercial benefits such as the production of efficient CdTe thin-film solar cells as well as reducing the environmental impact of the chlorine activation process.

在不到一小时的时间里到达地球的太阳能总量超过了全球每年的能源需求。太阳能电池通过将阳光转化为电能来提供宝贵的可再生能源。硅目前在太阳能电池技术中占据主导地位，尽管它本身对光的吸收能力很差。另一方面，薄膜太阳能电池利用强吸收材料，使材料体积减少到几微米厚的薄层，从而降低成本。薄膜太阳能电池的一个共同特点是具有高密度的晶体缺陷，这种缺陷被称为“晶界”。晶界划分了两个不同取向的晶体(即颗粒)相互碰撞的区域。它们通常会降低太阳能电池的整体效率，并且需要进行钝化以实现最佳的器件操作。事实上，在镉镉太阳能电池中，“氯激活”步骤是在沉积后使用的，在富氯环境中对器件进行退火热处理，从而使效率提高十倍。人们认为氯会分离到晶界从而钝化它们，尽管确切的机制尚不清楚。在这个项目中，我们将使用最先进的测量单个晶界的载流子寿命来探索氯活化背后的基本机制(S)。载流子寿命是表征给定晶界电活性及其对器件工作影响的重要参数。为了进行这类测量，必须将高空间分辨率(几纳米)与优良的时间分辨率(几皮秒)结合起来，这是最近才克服的技术要求。我们将使用最近安装在瑞士EPFL的新的Attolight扫描电子显微镜，对CdTe薄膜太阳能电池的晶界载流子寿命进行首次测量。这是世界上唯一一台能够进行此类分析的科学仪器。我们还将探索不同的氯活化方法(即使用固体氯化镉的标准活化方法和气体活化方法)对钝化晶界的相对有效性。这具有重要的长期商业效益，例如生产高效的镉镉薄膜太阳能电池，以及减少氯活化过程对环境的影响。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

A comparative study of microstructural stability and sulphur diffusion in CdS/CdTe photovoltaic devices

CdS/CdTe光伏器件微观结构稳定性和硫扩散的比较研究

DOI：
10.1016/j.solmat.2015.06.010
发表时间：
2015
期刊：
Solar Energy Materials and Solar Cells
影响因子：
6.9
作者：
Taylor A
通讯作者：
Taylor A

Nanometre-scale optical property fluctuations in Cu2ZnSnS4 revealed by low temperature cathodoluminescence

DOI：
10.1016/j.solmat.2017.08.028
发表时间：
2018
期刊：
Solar Energy Materials and Solar Cells
影响因子：
6.9
作者：
B. Mendis;A. Taylor;M. Guennou;D. Berg;M. Arasimowicz;Shafaat Ahmed;H. Deligianni;P. Dale
通讯作者：
B. Mendis;A. Taylor;M. Guennou;D. Berg;M. Arasimowicz;Shafaat Ahmed;H. Deligianni;P. Dale

Long Lifetime Hole Traps at Grain Boundaries in CdTe Thin-Film Photovoltaics.