Nanopyramid Structure for Ultrathin c-Si Tandem Solar Cells

Abstract

Recently, ultrathin crystalline silicon solar cells have gained tremendous interest because they are deemed to dramatically reduce material usage. However, the resulting conversion efficiency is still limited by the incomplete light absorption in such ultrathin devices. In this letter, we propose ultrathin a-Si/c-Si tandem solar cells with an efficient light trapping design, where a nanopyramid structure is introduced between the top and bottom cells. The superior light harvesting results in a 48% and 35% remarkable improvement of the short-circuit current density for the top and bottom cells, respectively. Meanwhile, the use of SiO x mixed-phase nanomaterial helps to provide the maximum light trapping without paying the price of reduced electrical performance, and conversion efficiencies of up to 13.3% have been achieved for the ultrathin tandem cell employing only 8 μm of silicon, which is 29% higher than the result obtained for the planar cell.

Realization of Quasi‐Omnidirectional Solar Cells with Superior Electrical Performance by All‐Solution‐Processed Si Nanopyramids

“…More details of the fabrication are presented in the Experimental Section. Compared to the present popular methods to form SiNPs, the MAAE method does not require etching pattern and thus does not involve lithography process or ion etching 27, 30, 31, 32. It only requires the deposition of Ag nanoparticles in solution before alkaline etching and is an all‐solution‐processed method.…”

“…On this aspect, Si nanopyramids (SiNPs) have extremely attracted interests due to the fact that they have low surface enhancement, while excellent antireflection and light trapping effect are retained 24, 25, 26, 27. Therefore, SiNPs have been successfully demonstrated to bring benefits for solar cells, especially in ultrathin c‐Si solar cells 28, 29, 30. However, we also notice that the knowledge on the angle‐dependent optical performance of SiNPs is very limited and it is also unknown whether the design of SiNPs is superior to SiMPs on solar cells.…”

“…We fabricated SiNPs on large‐scale (156 mm × 156 mm) wafers via our recently proposed metal‐assisted alkaline etching (MAAE) method,26 which is an all‐solution‐processed method and does not involve patterning process as required in the present popular methods 27, 30, 31, 32. We have excitingly found that the SiNPs can be easily passivated by intrinsic hydrogenated amorphous Si (i a‐Si:H) layer or SiN x :H layer and exhibit lower surface recombination compared to the conventional SiMPs counterparts, which is attributed to the lower surface enhancement.…”

Effects of intermediate plasmonic structures on the performance of ultra-thin-film tandem solar cells

“…To address these issues, thin-film and ultra-thin-film solar cells with multiple active layers are being investigated to reduce cost and increase efficiency. 4 Different nano-photonic techniques are being explored to increase the light absorption in thin-film and ultrathin-film tandem solar cells so that the cost can be reduced without sacrificing efficiency. [5][6][7][8][9][10] Two major problems that an ultra-thin-film tandem solar cell face are the very low absorption in ultra-thin active layers and the current mismatch between active layers.…”

Interface Magnetic and Electrical Properties of CoFeB /InAs Heterostructures

“…·cm [22], is only 10 times higher than that of CoFeB, i.e., =1.78×10 -4 ·cm [23]. This means that CoFeB/InAs heterostructure has low mismatch of resistivity, about two orders of magnitude lower than that of Fe/GaAs [24], promising high spin injection efficiency.…”