Improving Buried Interface Contact by Bidentate Anchoring for Inverted Perovskite Solar Cells.

Nickel oxide (NiOx) is a promising hole transport layer (HTL) to fabricate efficient and large-scale inverted perovskite solar cells (PSCs) due to its low cost and superior chemical stability. However, inverted PSCs based on NiOx are still lagging behind that of other HTL because of the poor quality of buried interface contact. Herein, a bidentate ligand, 4,6-bis (diphenylphosphino) phenoxazine (2DPP), is used to regulate the NiOx surface and perovskite buried interface. The diphosphine Lewis base in the 2DPP molecule can coordinate both with NiOx and lead ions at NiOx/perovskite interface, leading to high-quality perovskite films with minimized defects. It is found that the inverted PSCs with 2DPP-modified buried interface exhibit double advantages of being both fast charge extraction and reduced nonradiative recombination, which is a combination of multiple factors including favorable energetic alignment, improved interface contact and strong binding between NiOx/2DPP and perovskite. The optimal PSC based on 2DPP modification yields a champion power conversion efficiency (PCE) of 21.9%. The unencapsulated PSC maintains above 75% of its initial PCE in the air with a relative humidity (RH) of 30-40% for 1000 h.

Improving the performance of perovskite solar cells using a dual-hole transport layer.

The energy loss (Eloss) caused by inefficient charge transfer and large energy level offset at the buried interface can easily restrict the performance of p-i-n perovskite solar cells (PVSCs). In this study, the utilization of poly-TPD and P3CT-N as a dual-hole transporting layer (HTLs) was implemented in a sequential manner. This approach aimed to improve the charge transfer efficiency of the HTL and mitigate charge recombination at the interface between the HTL and PVK. The results showed that this strategy also could achieve more suitable energy levels, improve the quality of the perovskite film layer, and ultimately enhance the device's stability. IPVSCs employing the dual-HTLs approach exhibited the highest power conversion efficiency of 19.85%, and the open-circuit voltage increased to 1.09 V from 1.00 V. This study offers a straightforward and efficient approach to boost the device performance by minimizing Eloss and reducing the buried interfacial defects. The findings underscore the potential of employing a dual-HTL strategy as a promising pathway for further advancements in PVSCs.

Surface-induced phase engineering and defect passivation of perovskite nanograins for efficient red light-emitting diodes.

Organic-inorganic hybrid lead halide perovskites are potential candidates for next-generation light-emitting diodes (LEDs) in terms of tunable emission wavelengths, high electroluminescence efficiency, and excellent color purity. However, the device performance is still limited by severe non-radiative recombination losses and operational instability due to a high degree of defect states on the perovskite surface. Here, an effective surface engineering method is developed via the assistance of guanidinium iodide (GAI), which allows the formation of surface-2D heterophased perovskite nanograins and surface defect passivation due to the bonding with undercoordinated halide ions. Efficient and stable red-emission LEDs are realized with the improved optoelectronic properties of GAI-modified perovskite nanograins by suppressing the trap-mediated non-radiative recombination loss. The champion device with a high color purity at 692 nm achieves an external quantum efficiency of 17.1%, which is 2.3 times that of the control device. Furthermore, the operational stability is highly improved, showing a half-lifetime of 563 min at an initial luminance of 1000 cd m-2. The proposed GAI-assisted surface engineering is a promising approach for defect passivation and phase engineering in perovskite films to achieve high-performance perovskite LEDs.

A promising Ag2CrO4/LaFeO3 heterojunction photocatalyst applied to photo-Fenton degradation of RhB.

Ag2CrO4 nanoparticles (10-35 nm) were assembled onto LaFeO3 nanoparticles (20-60 nm) via a facile chemical precipitation method to form novel Ag2CrO4-LaFeO3 heterojunction composite photocatalysts. The prepared Ag2CrO4-LaFeO3 composites were characterized by XRD, SEM, TEM, XPS, BET, UV-vis DRS, PL spectroscopy and EIS and photocurrent response. The TEM result clearly shows that Ag2CrO4 particles are decorated onto LaFeO3 particles to form Ag2CrO4-LaFeO3 heterojunction. Compared to bare LaFeO3, the 10%Ag2CrO4-LaFeO3 composite exhibits a slightly increased BET specific surface area, increased photocurrent density, decreased charge-transfer resistance and decreased PL emission peaks. Using simulated sunlight as the light source and in the presence of H2O2, the photo-Fenton performance of the composite photocatalysts toward the degradation of RhB was investigated, revealing that they manifest significantly enhanced photo-Fenton degradation of RhB when compared with bare LaFeO3 and Ag2CrO4. Among the composite photocatalysts, 10%Ag2CrO4-LaFeO3 exhibits the highest photo-Fenton activity, which is about 3.1 and 2.5 times higher than that of bare LaFeO3 and Ag2CrO4, respectively. This is attributed to the fact that the composite photocatalysts have highly efficient separation of photogenerated electron-hole pairs due to the formation of Ag2CrO4-LaFeO3 heterojunctions. Active species trapping experiments and ·OH detection experiments were carried out, from which it is concluded that ·OH radicals are the dominant reactive species causing the dye degradation. A synergistic mechanism was proposed to elucidate the enhanced photo-Fenton activity of Ag2CrO4-LaFeO3 heterojunction composites.

Hierarchically Manipulated Charge Recombination for Mitigating Energy Loss in CsPbI2Br Solar Cells.

All-inorganic perovskite cesium lead iodide/bromide (CsPbI2Br) is considered as a robust absorber for perovskite solar cells (PSCs) because of its excellent thermal stability that guarantees its long-term operation stability. Efficient CsPbI2Br PSCs are available when obtaining low energy loss, which needs efficient charge generation, less charge recombination, and balanced charge extraction. However, numerous traps in perovskites hinder the photon-electron conversion process. Herein, hierarchical manipulation of charge recombination is proposed for CsPbI2Br PSCs featuring low energy loss. Nonselective trap reduction and selective halogen vacancy passivation are performed using 2,2'-(ethylenedioxy)diethylamine and phenylbutylammonium iodide for the bottom and top contacts, respectively. Because of all-around suppressed charge recombination, balanced charge extraction and suppressed hysteresis are realized. The champion PSC achieves an open-circuit voltage of 1.30 eV, a fill factor of 80.2%, and a power conversion efficiency of 16.6% that is 28.6% higher than that of the reference device. Moreover, the thermostability of PSCs is simultaneously enhanced because of the limited defect-assisted degradation.