III–V/Si epitaxial tandems with a 1.7-eV GaAsP top cell promise stable power conversion efficiencies above the fundamental limit of Si single-junction cells. However, III–V/Si epitaxial tandems have suffered from limited minority carrier diffusion length in the top cell, leading to reduced short-circuit current densities (J_SC) and efficiencies. While conventional wisdom dictates that dislocation density in III–V/Si tandems must be reduced to boost efficiency, here, we show that heterointerface design and growth sequence also play critical roles in reducing recombination losses. Our improved GaAsP cells make use of a wide-band gap AlGaAsP electron-blocking layer that forms a pristine interface with GaAsP, resulting in a 10%–20% (absolute) boost in quantum efficiency over previous work in the critical red wavelength range (600–725 nm), despite similar dislocation density. Combining the improved top cell carrier collection with Si backside texturing, we obtain 25.0% efficient GaAsP/Si tandem cells with a closely matched J_SC of 18.8 mA/cm².

具有1.7-eV GaAsP顶部电池的III-V / Si外延双极膜保证了稳定的功率转换效率，高于Si单结电池的基本极限。但是，III–V / Si外延双极膜受顶部单元中少数载流子扩散长度的限制，导致短路电流密度降低（J _SC）和效率。尽管传统观点认为必须降低III–V / Si薄膜中的位错密度以提高效率，但在这里，我们证明了异质界面设计和生长顺序在减少重组损失方面也起着关键作用。我们改良的GaAsP电池利用宽带隙AlGaAsP电子阻挡层与GaAsP形成原始界面，从而在临界红色波长范围内将量子效率比以前的工作提高了10％–20％（绝对）。 600-725 nm），尽管位错密度相似。结合改进的顶部电池载流子收集与Si背面纹理化，我们获得了25.0％的高效GaAsP / Si串联电池，其J _SC紧密匹配，为18.8 mA / cm ²。