Barugkin Chog, Allen Thomas, Chong Teck K, White Thomas P, Weber Klaus J, Catchpole Kylie R
Opt Express. 2015 Apr 6;23(7):A391-400. doi: 10.1364/OE.23.00A391.
The band-to-band absorption enhancement due to various types of light trapping structures is studied experimentally with photoluminescence (PL) on monocrystalline silicon wafers. Four basic light trapping structures are examined: reactive ion etched texture (RIE), metal-assisted etched texture (MET), random pyramid texture (RAN) and plasmonic Ag nanoparticles with a diffusive reflector (Ag/DR). We also compare two novel combined structures of front side RIE/rear side RAN and front side RIE/rear side Ag/DR. The use of photoluminescence allows us to measure the absorption due to band-to-band transitions only, and excludes parasitic absorption from free carriers and other sources. The measured absorptance spectra are used to calculate the maximum generation current for each structure, and the light trapping efficiency is compared to a recently-proposed figure of merit. The results show that by combining RIE with RAN and Ag/DR, we can fabricate two structures with excellent light trapping efficiencies of 55% and 52% respectively, which is well above previously reported values for similar wafer thicknesses. A comparison of the measured band-band absorption and the EQE of back-contact silicon solar cells demonstrates that PL extracted absorption provides a very good indication of long wavelength performance for high efficiency silicon solar cells.
利用单晶硅片上的光致发光（PL）对各种类型的光捕获结构导致的带间吸收增强进行了实验研究。研究了四种基本的光捕获结构：反应离子蚀刻纹理（RIE）、金属辅助蚀刻纹理（MET）、随机金字塔纹理（RAN）以及带有漫反射器的等离子体银纳米颗粒（Ag/DR）。我们还比较了正面RIE/背面RAN和正面RIE/背面Ag/DR这两种新型组合结构。光致发光的使用使我们能够仅测量由于带间跃迁引起的吸收，并排除自由载流子和其他来源的寄生吸收。测量的吸收光谱用于计算每种结构的最大产生电流，并将光捕获效率与最近提出的品质因数进行比较。结果表明，通过将RIE与RAN和Ag/DR相结合，我们可以制造出两种光捕获效率分别高达55%和52%的优异结构，这远高于先前报道的类似晶片厚度的值。对测量的带间吸收和背接触硅太阳能电池的外量子效率（EQE）的比较表明，PL提取的吸收为高效硅太阳能电池的长波长性能提供了很好的指示。
