Epitaxially grown quantum well and quantum dot solar cells suffer from weak light absorption, strongly limiting their performance. Light trapping based on optical resonances is particularly relevant for such devices to increase light absorption and thereby current generation. Compared to homogeneous media, the position of the quantum layers within the device is an additional parameter that can strongly influence resonant absorption. However, this effect has so far received little attention from the photovoltaic community. We develop a theoretical framework to evaluate and optimize resonant light absorption in a thin slab with multiple quantum layers. Using numerical simulations, we show that the position of the layers can make the difference between strong absorption enhancement and completely suppressed absorption, and that an optimal position leads to a resonant absorption enhancement two times larger than average. We confirm these results experimentally by measuring the absorption enhancement from photoluminescence spectra in InAs/GaAs quantum dot samples. Overall, this work provides an additional degree of freedom to substantially improve absorption, encouraging the development of quantum wells and quantum dots-based devices such as intermediate-band solar cells.

中文翻译：

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多层量子阱和量子点太阳能电池的共振吸收

外延生长的量子阱和量子点太阳能电池的光吸收较弱，极大地限制了它们的性能。基于光学共振的光捕获与此类设备特别相关，以增加光吸收并因此增加电流产生。与均质介质相比，器件内量子层的位置是一个附加参数，可以强烈影响共振吸收。然而，到目前为止，这种效应很少受到光伏界的关注。我们开发了一个理论框架来评估和优化具有多个量子层的薄板中的共振光吸收。使用数值模拟，我们表明层的位置可以在强吸收增强和完全抑制吸收之间产生差异，并且最佳位置导致共振吸收增强比平均值大两倍。我们通过测量 InAs/GaAs 量子点样品中光致发光光谱的吸收增强来实验证实这些结果。总体而言，这项工作提供了额外的自由度以显着改善吸收，鼓励开发量子阱和基于量子点的器件，例如中波段太阳能电池。