We report on the noise analysis of high performance germanium quantum dot (Ge QD) photodetectors with responsivity up to $2 A/W and internal quantum efficiency up to $400%, over the 400-1100 nm wavelength range and at a reverse bias of À10 V. Photolithography was performed to define variable active-area devices that show suppressed dark current, leading to a higher signal-to-noise ratio, up to 10 5 , and specific detectivity D Ã ' 6 Â 10 12 cm Hz 1=2 W À1. These figures of merit suggest Ge QDs as a promising alternative material for high-performance photodetectors working in the visible to near-infrared spectral range.
We report on plasmon-enhanced hybrid organic−inorganic perovskite solar cells with methylammonium lead iodide (MAPbI 3 ) as the active absorbing material. Three-dimensional finite-difference time-domain simulations were performed on perovskite solar cells that consist of perovskite films with varied thicknesses on top of corrugated gold electrodes with different light trapping geometries, such as arrays of nanoholes and nanodisks. The absorption within the perovskite and gold films was estimated by calculating the electric field at every mesh point within the simulation volume, which allowed for the calculation of the solar cell power conversion efficiency (PCE) as a function of relevant design parameters. Optimal nanostructure designs were obtained by systematically varying the geometry dimensions. The results show that 100 nm-thick perovskite films on top of corrugated gold electrodes can exhibit up to 52% increase in PCE compared to their flat counterparts (i.e., from 19.2% for a flat cell to 29.2% for an optimized nanocorrugated cell). Moreover, we show that a 150 nm-thick perovskite film cell with opportunely corrugated back metal contacts can exhibit a PCE value of 31.3%, which is comparable to that of a 400 nm-thick bulk-like cell (31.6%). These findings may pave the way for plasmon-enhanced high-performance perovskite solar cells with ultrathin absorbing layers.
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