[6,6]-Phenyl-C₆₁-Butyric Acid Methyl Ester/Cerium Oxide Bilayer Structure as Efficient and Stable Electron Transport Layer for Inverted Perovskite Solar Cells

Abstract

Stability issues and high material cost constitute the biggest obstacles of a perovskite solar cell (PVSC), hampering its sustainable development. Herein, we demonstrate that, after suitable surface modification, the low-cost cerium oxide (CeO ) nanocrystals can be well dispersed in both polar and nonpolar solvents and easily processed into high-quality electron transport layers (ETLs). The inverted PVSC with the configuration of "NiMgLiO/MAPbI/[6,6]-phenyl-C-butyric acid methyl ester (PCBM)/CeO " has achieved a high efficiency up to 18.7%. Especially, the corresponding devices without encapsulation can almost keep their initial PCEs in 30% humidity-controlled air in the dark for 30 days and also show no sign of degradation after continuous light soaking and maximum power point tracking for 200 h in a N atmosphere. These results have been proved to be associated with the dual functions achieved by the PCBM/CeO bilayer ETLs in both efficient electron extraction and good chemical shielding. Furthermore, an all inorganic interfacial layer based PVSC with the configuration of "NiMgLiO/MAPbI/CeO " has also achieved a promising efficiency of 16.7%, reflecting the potential to fabricate efficient PVSCs with extremely low cost.

Enhancing the Open‐Circuit Voltage of Perovskite Solar Cells by up to 120 mV Using π‐Extended Phosphoniumfluorene Electrolytes as Hole Blocking Layers

“…As expected, the bare PCBM control device exhibits a low fill factor (FF) of 60.1% and a moderate open circuit voltage ( V OC ) of 0.96 V, leading to a PCE of only 12.85%. The J – V characteristics of this device shows an S‐shape originating from a high series resistance and poor hole‐blocking, in agreement with previous reports . The introduction of any HBL (BCP/π‐PFEs) eliminates the S‐shape, significantly increasing the FF of the devices.…”

Perovskite Solar Cells Using Surface‐Modified NiOx Nanoparticles as Hole Transport Materials in n‐i‐p Configuration

“…For the spectrum for HA, there are three bands at 2932, 2852, and 1706 cm −1 , which are assigned to the stretching vibrations of —CH 2 —CH 3 , —CH 2 —CH 2 — of the alkyl chain and the stretching C═O of the carboxyl unit, respectively. The spectrum of the NiO x –HA NPs exhibited the stretching vibration of the alkyl chain at 2926 and 2846 cm −1 and the asymmetric and symmetric stretching of COO − group at 1544 and 1408 cm −1 , in which the band at 1706 cm −1 for the stretching C═O disappeared . The broadband at ≈3500 cm −1 for pristine NiO x and NiO x –HA is due to the stretching vibration of hydroxyl groups on the surface of NPs .…”

Zn0.8Cd0.2S@PCBM Hybrid as an Efficient Electron Transport Layer for Air‐Processed p‐i‐n Planar Perovskite Solar Cells: Improvement of Interfacial Electron Transfer and Device Stability

“…As shown in Figure e–g, the presence of Zn, Cd, and S elements in the ETL layer can be verified, and the ZCS nanoparticles are uniformly dispersed in the PCBM film. The ZCS nanoparticles act as barriers to protect the perovskite from the erosion by the ambient moisture, which is helpful to improve the device stability …”

“…However, it should be mentioned that the dispersion and viscosity of inorganic solutions are quite limited, leading to defective film morphology and low film coverage on the perovskite surface, limiting the reproducibility of device performance. Fang et al proposed a method that combines organic PCBM and inorganic CeO x as a bilayer ETL, resulting in a PCE of 18.7% and good stability with ≈90% of the initial PCE retained after 200 h storage in the air of 30% relative humidity. By comparison with the above two techniques, straightly imbedding inorganic dopants into the PCBM layer to form a hybrid ETL displays simpler and more effective, being advantageous to further improve the performance and stability of PSCs.…”