Sheng-Hsiung Yang

Perovskite solar cells (PSCs) are promising next-generation energy technologies owing to their high efficiency, low material consumption, and solution processability.

The pyridine-based Co-SAM molecule 4-PAA was utilized to improve the surface coverage of MeO-2PACz and grain growth of perovskite films through hydrogen bonding.

The DPAI and DPABr ligands compensated for surface defects of perovskite nanocrystals through released I ⁻ and Br ⁻ anions and improved charge carrier injection by π-conjugated benzene rings.

To reduce surface defects and tune mismatched energy levels between the tin oxide (SnO₂) electron transport layer (ETL) and perovskite absorber, a mixture of urea and potassium acetate (U‐PA) is firstly utilized as a healing agent. The perovskite film deposited on the SnO₂/U‐PA layer exhibits enlarged grains and shortened carrier lifetime compared to that on the pristine SnO₂. The U‐PA treatment not only ameliorates the photocurrent but also adjusts interfacial energy level alignment, thereby reducing the energy barrier and augmenting open‐circuit voltage (V_OC) of the photovoltaic devices. The device based on the SnO₂/U‐PA ETL leads to the best conversion efficiency breakthrough of 19.24% and a high V_OC of 1084.5 mV, which are much higher than those of the controlled device. Moreover, the unencapsulated device retains 70% of its initial efficiency after 800 h storage. The experimental results provide a facile and inexpensive guidance toward sustainable green energy production.

The recombination of charge carriers at the interface between carrier transport layers such as nickel oxide (NiO_x) and the perovskite absorber has long been a challenge in perovskite solar cells (PSCs). To address this issue, we introduced a polymer additive poly(vinyl butyral) into NiO_x and subjected it to high-temperature annealing to form a void-containing structure. The formation of voids is confirmed to increase light transmittance and surface area of NiO_x, which is beneficial for light absorption and carrier separation within PSCs. Experimental results demonstrate that the incorporation of the polymer additive helped to enhance the hole conductivity and carrier extraction of NiO_x with a higher Ni³⁺/Ni²⁺ ratio. This also optimized the energy levels of NiO_x to match with the perovskite to raise the open-circuit voltage to 1.01 V. By incorporating an additional NiO_x layer beneath the polymer-modified NiO_x, the device efficiency was further increased as verified from the dark current measurement of devices.

The bromide (Br) ions on a conjugated polyelectrolyte (CPE) PFN-Br were converted to tetrafluoroborate (BF₄) or hexafluorophosphate (PF₆) ions through anion exchange to obtain two polymers PFN-BF₄ or PFN-PF₆ for surface engineering of zinc oxide nanocrystals (ZnO NCs). The ionic groups on CPEs can form permanent dipoles to facilitate charge injection from ZnO NCs to cesium lead bromide (CsPbBr₃) NCs emitters and therefore promote luminescent properties of inverted perovskite light-emitting diodes (PeLEDs). The incorporation of CPEs also helped to passivate the defects of ZnO NCs films, improve contact between ZnO and perovskite layers, and prolong carrier lifetime of CsPbBr₃ NCs. PeLEDs based on different CPEs were fabricated and evaluated.

This study aims to enhance the optical and thermal properties of cesium-based perovskite nanocrystals (NCs) through surface passivation with organic sulfonate (or sulfonic acid) ligands. Four different phenylated ligands, including sodium β-styrenesulfonate (SbSS), sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (SPTS), and 4-dodecylbenzenesulfonic acid (DBSA), were employed to modify blue-emitting CsPbBr_1.5Cl_1.5 perovskite NCs, resulting in improved size uniformity and surface functionalization. Transmission electron microscopy and X-ray photoelectron spectroscopy confirmed the successful anchoring of sulfonate or sulfonic acid ligands on the surface of perovskite NCs. Moreover, the photoluminescence quantum yield increased from 32% of the original perovskite NCs to 63% of the SPTS-modified ones due to effective surface passivation. Time-resolved photoluminescence decay measurements revealed extended PL lifetimes for ligand-modified NCs, indicative of reduced nonradiative recombination. Thermal stability studies demonstrated that the SPTS-modified NCs retained nearly 80% of the initial PL intensity when heated at 60 °C for 10 min, surpassing the performance of the original NCs. These findings emphasize the optical and thermal stability enhancement of cesium-based perovskite NCs through surface passivation with suitable sulfonate ligands.

ZnO nanoparticles (NPs) with excellent optoelectronic properties are widely used as electron transport layers (ETLs) in quantum dot light-emitting diodes (QLEDs). However, the high conductivity of ZnO can lead to charge imbalance and exciton quenching at the emission layer (EML)/ETL interface, seriously limiting the device performance. In this research, three phenylated sulfonate ligands, including sodium benzenesulfonate (SBS), sodium p-toluenesulfonate (STS), and sodium beta-styrenesulfonate (SβSS), were solely introduced onto the ZnO NP surface. Smooth and compact surfaces of ZnO films were obtained after introducing phenylated sulfonate ligands. Additionally, an upward shift in the energy levels of ZnO was observed, leading to a reduction in electron transport and thereby alleviating excess electron injection. The optimized QLED using the SβSS-modified ZnO ETL exhibited the best performance with a maximum luminance of 458 810 cd m⁻² and a peak current efficiency of 40.1 cd A⁻¹, which were enhanced by 60.6% and 64.1% compared with those of the control device based on the pristine ZnO ETL. Meanwhile, an extrapolated device lifetime exceeding 1073 hours was anticipated that was 9.3-fold longer than that of the control device. Our experiments demonstrate the impact of phenylated sulfonate molecules on the surface modification of ZnO NPs and the performance of QLEDs, providing valuable insights and support for future developments.