Search

Nickel oxide (NiOX) has a crucial role in enhancing the efficiency and stability of p‐i‐n inverted perovskite solar cells (PSCs), which hold great potential for commercialization. However, improving contact passivation between perovskites and NiOX is a challenge due to a hindered buried interface. In order to address this issue, self‐assembled monolayers (SAMs) are introduced as a buffer layer to prevent direct contact and non‐radiative recombination. While, the large dipole moment of SAMs increases the work function of NiOX, which is crucial for enhancing hole transport performance, given the low interfacial potential barrier for hole transfer. By a combination of the first‐principles calculations, drive‐level capacitance profiling, and transient absorption spectrum characterization, the understanding of the ion‐dipole interactions and interface passivation mechanism of potassium fluoride (KF) ultra‐thin buffer layer between SAMs and perovskites is provided. The efficiency of inverted PSCs as high as 23.25% is obtained, and the unencapsulated devices kept 90% of initial efficiency following 1400 h aging under nitrogen, which demonstrate remarkable long‐term stability as well. This novel strategy highlights the significance of SAMs dipole moment at the NiOX/perovskites interface and provides a new approach to address buried interfaces for high‐efficiency and long‐term stability in inverted PSCs. [ABSTRACT FROM AUTHOR]

The multilevel encoding (MLE) scheme is an effective method for improving the anticounterfeiting encryption capabilities of physically unclonable functions (PUFs). However, owing to the correlation between encoding layers, the encoding capacity (EC) is difficult to improve by orders of magnitude. Herein, four noncorrelated structures in the diamond crystal structure (carbon–carbon single bond, defect luminescence structures, spin structures, and electron energy distribution structures) are considered for MLE. First, the microdiamonds containing nitrogen‐vacancy (NV) color centers are embedded into polydimethylsiloxane (PDMS) to fabricate PUFs. Using an optical imaging system, four codable images of four noncorrelated structures are read. The noncorrelation of the four‐level encoding structure is verified by calculating the Hamming distance (0.496 ± 0.02). The results show that EC exponentially improves to 24×10 000/(100 pixels)2. Furthermore, the encoding method based on the energy level does not depend on physical structure parameters, such as the size and position of the spin structure. Thus, it is protected from structural modeling attacks, resulting in high security. Moreover, PUF labels based on PDMS flexible substrates can be employed for various flexible applications. In the proposed scheme, the information is encrypted by a four‐level two‐dimensional (2D) barcode and decoded by self‐developed PUF authentication software. The proposed scheme presents a way for developing next‐generation PUFs with super‐high EC. [ABSTRACT FROM AUTHOR]

The fragile bottom side of perovskite films is demonstrated to be harmful to the efficiency and stability of perovskite solar cells (PSCs) because the carrier extraction and recombination can be significantly influenced by the easily formed strain, voids, and defects on the bottom side. Nevertheless, the bottom side of perovskite films is usually overlooked because it remains a challenge to directly characterize and modify the bottom side. Herein, a facile and effective strategy is reported to stabilize the bottom side via preburying cesium formate (CsFo) into the SnO2 electron transport layer (ETL). It is found that the synergistic effect of cesium cation (Cs+) and formate anion (HCOO−) causes strain relaxation, void elimination, and defects' reduction, which further facilitate the charge extraction. Consequently, the champion power conversion efficiency (PCE) of formamidinium (FA)‐based PSCs is increased from 23.34% to 24.50%. Meanwhile, the ultraviolet (UV), thermal, and operational stability are also enhanced. Finally, formamidinium–cesium (FACs)‐based PSCs are investigated to confirm the effectiveness of this preburied CsFo strategy, and the optimal device exhibits a champion PCE of 25.03% and a remarkably high fill factor (FF) of 85.65%. [ABSTRACT FROM AUTHOR]