With the emergence of highly efficient perovskite solar cells in both single- and multijunction architectures, there is an abundance of reports of extremely high external quantum efficiencies (EQE) up to 98%. Typically, the spectral maximum of the EQE is found in the range between 400 and 500 nm, which is even more surprising, as the transmittance of typically used indium tin oxide (ITO)/glass substrates does not exceed 90% in this wavelength range. Herein, the root cause of the high EQE values by a combination of experimental data and optical simulations is analyzed and explained. It is shown that the high refractive index of the perovskite absorber is strongly increasing the transmittance of incident light into the active perovskite layer, while the spectral distribution and ultimately the spectral position of the peak in the transmittance spectrum are strongly affected by the thickness and optical properties of the underlying transparent electrode.

中文翻译：

---

钙钛矿太阳能电池中近统一外量子效率的光学起源

随着单结和多结结构中高效钙钛矿太阳能电池的出现，有大量关于高达 98% 的极高外部量子效率 (EQE) 的报道。通常，EQE 的光谱最大值在 400 到 500 nm 之间的范围内，这更令人惊讶，因为通常使用的氧化铟锡 (ITO)/玻璃基板的透射率在此波长范围内不超过 90%。在此，通过实验数据和光学模拟相结合，分析和解释了高 EQE 值的根本原因。结果表明，钙钛矿吸收体的高折射率极大地增加了入射光进入活性钙钛矿层的透射率，