Quantum-assisted photoelectric gain effects in perovskite solar cells

Further boosting the power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) without excessively increasing production expenses is critical for practical applications. Here, we introduce silicon quantum dots (SiQDs) to enable perovskites to harvest additional sunlight without changing PSC processes. These SiQDs can convert shorter wavelength excitation light (300–530 nm) into visible region light and reflect longer wavelength perovskite-unabsorbed visible light (550–800 nm), leading to broadband light absorption enhancement in PSCs. As a result, the SiQD-based photocurrent gain can improve the external quantum efficiencies of PSCs over a wide wavelength range of 360–760 nm, yielding relatively enhanced short-circuit current density (+1.66 mA/cm²) and PCE (+1.4%). Surprisingly, even the PSC with a low-purity perovskite layer shows an ultrahigh PCE improvement of 5.6%. Our findings demonstrate QD-assisted effects based on earth-abundant and environmentally friendly silicon, leading to effective optical management that remarkably promotes the performance of PSCs and enables the balance of costs to be substantially addressed.