NdCl₃ Dose as a Universal Approach for High-Efficiency Perovskite Solar Cells Based on Low-Temperature-Processed SnO_x

Abstract

The defects on the surface of low-temperatureprocessed electronic transport layers hindered the development of efficient flexible perovskite solar cells. Herein, we develop a universal NdCl 3 dosing strategy to circumvent the residual Sn(II)−OH defects from the incomplete wet-chemical reaction. The introduction of NdCl 3 does not lead to the doping of Nd 3+ ions but rather the formation of a composite film of NdCl 3 with SnO x . The dose of NdCl 3 effectively reduces surface trap states at low-temperatureprocessed SnO x films, leading to increased carrier extraction and reduced carrier accumulation/recombination at the ETL/perovskite interface. These improvements result in perovskite solar cells (PvSCs) with significantly enhanced power conversion efficiency (PCE) and eliminated hysteresis. Finally, efficiencies of 18.62% and 21.49% for PvSCs based on MAPbI 3 and FA 1−x MA x PbI 3 perovskites, respectively, were achieved on rigid substrates. The test on a flexible device based on Cs 0.05 (FA 0.83 MA 0.17 ) 0.95 (I 0.83 Br 0.17 ) 3 perovskite realized a PCE of 16.14% and an incredible V OC of 1.158 V. This study indicated the potential of NdCl 3 dose as a universal approach to enhance the performance of PvSCs with low-temperatureprocessed SnO x ETL.

Rear Interface Engineering to Suppress Migration of Iodide Ions for Efficient Perovskite Solar Cells with Minimized Hysteresis

“…The perovskite film deposited on NdCl 3 -IL showed significantly lower photoluminescence intensity than that of control when excited from the ETL side, while almost identical photoluminescences were seen when both films were excited from the perovskite side (see in Figure S14, Supporting Information), which demonstrates more effective carrier extraction at the rear interface in NdCl 3 -IL device. [61][62][63]14] In addition, the NdCl 3 -IL device showed faster photoluminescence decay constants according to the time-resolved photoluminescence (TRPL) spectra excited from the ETL side, demonstrating the better carrier extraction and reduced trap states at the rear interface [6,64] (Figure 6b and Table S5, Supporting Information).…”

“…Figure a shows the n–i–p‐type planar junction device structure used in this study and the schematic illustration of thermally evaporated NdCl 3 ‐IL on the SnO 2 electron transport layer (ETL) The X‐ray photoelectron spectra (XPS) measurement on the film with NdCl 3 ‐IL showed prominent characteristic peaks of Nd 4d and Cl 2p states at 123.4 and 198.5 eV, demonstrating that the NdCl 3 ‐IL has been successfully evaporated onto the ETL surface [ 6 ] (Figure S1, Supporting Information).…”

Optimization of SnO2 electron transport layer for efficient planar perovskite solar cells with very low hysteresis

“…9 Therefore, many alternative n-type wide bandgap semiconductors -such as SnO 2 , ZnO, WO 3 , In 2 O 3 , Zn 2 SnO 4 , SrTiO 3 , BaSnO 3 , Ba 0.8 Sr 0.2 SnO 3 and Nb 2 O 5 -have been studied as ETLs for the realization of high-performance, planar, and low-temperature-processed n-i-p PSCs. [10][11][12] SnO 2 has been identified as one of the most promising candidates owing to its favourable optoelectronic properties, 13,14 including low light absorption, appropriate energy level alignment with the perovskite, high electron mobility as well as low-temperature processing. [13][14][15][16][17][18] However, planar PSCs employing 'standard' SnO 2 ETLswithout any additive or interface modification -often suffer from considerable current-voltage (J-V) hysteresis that limits the PCE of such devices.…”

cPCN-Regulated SnO2 Composites Enables Perovskite Solar Cell with Efficiency Beyond 23%

“…However, charge accumulation may happen at the SnO 2 /perovskite interface resulting in severe hysteresis due to much lower electron mobility of SnO 2 ETL than perovskite absorbers (0.5–30 cm 2 V −1 s −1 ) [ 19 – 22 ]. To alleviate the hysteresis effect, dopants or additives such as metal cations and polymers were added to enhance the conductivity of SnO 2 and hence the PCE of devices.…”