Fabry-Perot-type resonant nanocavities allow for broadband enhancement of light absorption in ultrathin absorber layers. By introducing a switchable mirror, these thin film structures can be used as unique optical devices enabling interesting applications with switchable absorption. We use a thin film photovoltaic layer stack based on an amorphous germanium absorber layer and combine it with a thin Mg/Pd mirror to create a switchable solar cell. In this work we demonstrate how we can switch the light absorption and, hence, the photocurrent generation of the thin film solar cell by changing the refractive index of Mg due to hydrogen absorption. Our results show how optical resonances in the absorber can be switched “on/off” by the change of optical properties of the magnesium reflector. The multilayer system can be switched from a light absorbing and photocurrent generating state to a transparent window state with excellent color neutrality. We emphasize our study as an important step toward the realization of switchable photovoltaic windows, which paves the way for larger scale building integrated photovoltaic applications.

中文翻译：

---

超薄谐振腔太阳能电池中的可切换光电流产生

法布里-珀罗（Fabry-Perot）型共振纳米腔可在宽带上增强超薄吸收层中的光吸收。通过引入可切换反射镜，这些薄膜结构可以用作独特的光学器件，从而实现具有可切换吸收的有趣应用。我们使用基于非晶锗吸收层的薄膜光伏层堆叠，并将其与薄Mg / Pd反射镜组合在一起以创建可切换的太阳能电池。在这项工作中，我们演示了如何通过改变由于氢吸收而引起的Mg的折射率，来改变薄膜太阳能电池的光吸收，从而改变光电流的产生。我们的结果表明，如何通过改变镁反射镜的光学特性来“打开/关闭”吸收器中的光学共振。多层系统可以从吸收光和产生光电流的状态切换到具有优异的颜色中性的透明窗口状态。我们强调我们的研究是迈向实现可切换光伏窗户的重要一步，这为大规模建筑集成光伏应用铺平了道路。