Complementary absorption effect to improve the optical efficiency of dual-absorption-layered PSCs

By taking advantage of the complementary absorption effect of germanium (Ge) and perovskite, a novel perovskite solar cell (PSC) was proposed by stacking Ge and perovskite thin films to serve as the dual absorption layer. Its absorption spectra and photocurrent were calculated and optimized as a function of the thickness of Ge film by finite element method (FEM). Then, the optical efficiency was further boosted by embedding an array of Ge semi-ellipsoidal nanoparticles within the perovskite film. The predicted maximum photocurrent is revealed to reach 45.72mA/cm2, which is 2.55 times larger than that of planar referenced PSC. Besides the complementary absorption effect, the localized surface plasmon resonance (LSPR) of Ge nanoparticles and the grating effects of Ge nanoparticle array are revealed to contribute to the obtained Jsc improvement. The present work is insightful for future design and applications of PSCs by introducing Ge thin film and Ge nanoparticles.