TiO2/SnO2 Bilayer Electron Transport Layer for High Efficiency Perovskite Solar Cells

Abstract

The electron transport layer (ETL) has been extensively investigated as one of the important components to construct high-performance perovskite solar cells (PSCs). Among them, inorganic semiconducting metal oxides such as titanium dioxide (TiO2), and tin oxide (SnO2) present great advantages in both fabrication and efficiency. However, the surface defects and uniformity are still concerns for high performance devices. Here, we demonstrated a bilayer ETL architecture PSC in which the ETL is composed of a chemical-bath-deposition-based TiO2 thin layer and a spin-coating-based SnO2 thin layer. Such a bilayer-structure ETL can not only produce a larger grain size of PSCs, but also provide a higher current density and a reduced hysteresis. Compared to the mono-ETL PCSs with a low efficiency of 16.16%, the bilayer ETL device features a higher efficiency of 17.64%, accomplished with an open-circuit voltage of 1.041 V, short-circuit current density of 22.58 mA/cm2, and a filling factor of 75.0%, respectively. These results highlight the unique potential of TiO2/SnO2 combined bilayer ETL architecture, paving a new way to fabricate high-performance and low-hysteresis PSCs.

Upper Subcell Impacts on Perovskite/u-CIGS Tandem Solar Cell Performance

“…Interestingly, efficiency becomes almost constant with the entire interface density range until 1 × 10 12 cm -2 as illustrated in Figure 5. Using simulation results, we conclude that the defect density at absorber/HTL and ETL/absorber interfaces has a strong effect on both J sc and V oc [38][39][40]. Therefore, the interfaces and the interfacial materials need to be carefully engineered and developed to avoid all the problematic aspects [39,43].…”

“…Due to the ionic nature of perovskite materials, they can display different states of a defect [28,36,37]. Furthermore, the deep defect states in the bandgap of an absorber can crucially limit the cell performance by causing carrier trapping, non-radiative recombination, and hysteresis effect in the J-V curves of PSCs [36][37][38][39][40][41][42][43]. All these factors cause a significant impact on reducing the PCE of PSCs [28,38].…”

“…An increase in N t causes cell degradation due to a negative impact of the recombination mechanism on generated carriers. The carrier diffusion length may increase by lowering the absorber's defect density, thereby enhancing solar cell device performance [36][37][38][39][40][41].…”

“…The energy barrier or poor charge transport capability (high defect and low carrier mobility) of the ETL or HTL causes charge accumulation at the interfaces ETL/absorber or absorber/HTL which limits the charge extraction and increases recombination [38][39][40]. These issues can reduce the anode/cathode contact charge collection efficiency [38][39][40]. Therefore, it may be possible to increase J-V hysteresis and light soaking effect in the PSCs [39].…”

Editorial for the Special Issue “Amorphous and Nanocrystalline Semiconductors: Selected Papers from ICANS 29”

“…This includes topics such as Si-based, oxide, perovskite, 2D thin films and nanostructures, device applications for TFTs, solar cells, and LEDs, as well as memory devices and emerging flexible electronics and neuromorphic applications. For example, new fabrication technologies of amorphous and nanocrystalline thin films, electronic and optical characteristics, and device applications are presented and discussed in [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ], including theoretical work in an ab initio study [ 9 ], controllable growth and formation of Si nanowires [ 1 ], nanocrystals [ 2 ], and quantum dots [ 3 , 4 ]. There are also several papers that cover emerging memory devices.…”