Inverse Design of High Absorption Thin-Film Photovoltaic Materials
Inverse Design of High Absorption Thin-Film Photovoltaic Materials
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DOI：
10.1002/aenm.201200538
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发表时间：
2013-01-01
影响因子：
27.8
通讯作者：
Zunger, Alex
中科院分区：
文献类型：
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作者：
Yu, Liping;Kokenyesi, Robert S.;Zunger, Alex
通过帮助漂移通过一个非常薄的无机吸收膜的光生载流子收集增强代表了一个有前途的路线，新的，高效率的光伏（PV）器件。[1]这种器件的实现主要取决于在带隙处突然出现的整个太阳光谱上表现出强吸收的材料的可用性。这种材料具有直接带隙，但不是所有的直接带隙材料都是强吸收体。目前，以CuInSe 2为代表的三元I-III-VI 2硫属化物是已知的强直接带隙吸收剂之一，为商业薄膜太阳能电池技术奠定了基础。虽然整体吸收很强，但在带隙附近测得的弱吸收需要使用相当厚的薄膜（约1.5 μm）。[2]这种厚度加上相对较低的In丰度（In/Si= 10− 7）可能会限制该技术的可扩展性到太瓦级。[3]显然，通过识别和设计新的强吸收材料来推进最先进的薄膜光伏的机会是存在的。然而，目前还没有指导性规则（“设计原则”）来揭示区分强、中或弱直接带隙吸收体的物理因素。在这项工作中，我们提出了一个基本的分析的因素，控制吸收强度的化合物半导体。从这个分析中，我们对“吸收设计原理”有了新的认识，提出了候选的高吸收材料，并通过实验评估了它们的吸收性能。所需材料的识别和设计需要一种超越经典一维Shockley-Queisser标准的方法，[4]其仅基于它们的带隙（直接或间接）在1.0 - 1.5 eV的范围内来选择良好的PV吸收剂。这个简单的一维度量并不代表材料相关的光学吸收光谱和相关的辐射/非辐射复合损耗，这对于评估半导体作为薄膜吸收体是必不可少的。最近，我们提出了一种新的和改进的
Enhancement of photocarrier collection by aiding drift through a very thin inorganic absorber film represents a promising route to new, high-efficiency photovoltaic (PV) devices.[1] The realization of such devices is largely predicated on the availability of materials that exhibit strong absorption across the solar spectrum with an abrupt onset at the band gap. Such materials have direct band gaps, but not all direct-band-gap materials are strong absorbers. Currently, ternary I-III-VI 2 chalcogenides, typified by CuInSe 2, are among the strong direct band-gap absorbers known, establishing the basis for a commercial thinfilm solar cell technology. While overall absorption is strong, the measured weak onset absorption near the band gap necessitates the use of rather thick films (∼ 1.5 μm).[2] This thickness coupled with the relatively low abundance of In (In/Si= 10− 7) potentially limits the scalability of this technology to the terawatt level.[3] Clearly, opportunities exist for advancing state-ofthe-art thin-film PV through identification and design of new, strongly absorbing materials. However, there are currently no guiding rules (“design principles”) that reveal the physical factors distinguishing strong from moderate or weak direct-bandgap absorbers. In this work, we present a fundamental analysis of the factors that control absorption strength in compound semiconductors. From this analysis, we develop new insights into “absorption design principles”, propose candidate, highly absorbing materials, and experimentally assess their absorption properties.Identification and design of the needed materials requires an approach beyond the classic one-dimensional Shockley-Queisser criterion,[4] which selects good PV absorbers solely on the basis of their band gap (direct or indirect) being in the range of 1.0− 1.5 eV. This simple one-dimensional metric does not represent material-dependent optical absorption spectra and related radiative/nonradiative recombination losses, which are essential for evaluating a semiconductor as a thin-film absorber. Recently, we have proposed a new and improved