Quantum Dot Enabled Perovskite Thin Film with Enhanced Crystallization, Stability, and Carrier Diffusion via Pulsed Laser Nanoengineering

Abstract

transport dynamics, which is the key for high-performance perovskite devices. At present, precursor solution additive as a convenient and effective method has been widely used in the structural optimization of perovskite films, [8] such as doping in the perovskite lattice to form bonds, [9] and additives to form hydrogen bonds with perovskites. [10] Quantum dots (QDs) are often doped in perovskite grain boundaries to reduce the boundary barrier for promoting the transport of photogenic carriers. [11] In addition, additives to prevent water/oxygen penetration by forming strong chemical bonds at the interface are important way to improve the stability of perovskite films. [12] Although precursor solution additive method provides an excellent material based for the structural optimization, the current postprocessing methods are limited to fabricate crystalline perovskite films to control their structure and properties, due to the challenges in manipulate the heating/cooling rate, residual stress, and microstructure, such as grain size, intragrain defects, and grain boundary defects. Laser has been widely used in semiconductor processing because of its advantages of monochromatism, coherence, directionality, high speed processing, scalability, wide range control of energy density, and wavelength. The laser-assisted processing technology was developed for rapid processing of perovskite, [13] which can facilitate the postprocessing of perovskite devices with high speed. Moreover, compared with the traditional thermal annealing, the energy consumption of laser treatment is much less. [14] In addition, The temperature control at the material interface, such as grain boundaries, is critical for defect density, and phases, which are important for high-performance perovskite-based optoelectronic devices. However, it is challenging to fine-tune the microstructures in perovskite films with well-controlled grain structure, interface defects, porosity, phase structure, and strains, simultaneously. Here, pulsed laser technology is combined with carbon quantum dots (CQDs) into perovskite absorbers with pore-free, less defect, high crystallinity, enhanced absorption, low stress, and phase-stabilized microstructures. Due to laser-CQD interaction-induced grain boundary microstructure changes, perovskite films can be fabricated with much larger grains (>10 times) than those after thermal annealing. As CQDs are embedded to passivate grain, this leads to reduced grain boundary barrier at the interface, which significantly improve the carrier transportation in perovskite films. The shift of perovskite band to vacuum energy level leads to remarkable improvement of carrier extraction efficiency and lifetime, leading to much higher mobility of photogenerated carriers and diffusion length (>1 μm). The laser-induced thermomechanical momentum significantly enhances crystal interface with hydrophobic perovskite film, resulting in much less residual tensile stress by 20 times and excellent stability. Pulsed-laser-assisted QD additive engineerin...

Phase Nanoengineering via Thermal Scanning Probe Lithography and Direct Laser Writing

“…In this context, it was recently shown that by scanning a pulsed laser over carbon quantum dots implanted into a perovskite thin film, the resulting grain boundaries are much larger than those following standard thermal annealing, yielding enhanced crystallinity and phase stability. [115] Thermal scanning probe lithography and direct laser writing are extremely versatile techniques for patterning nanostructures on different materials. On the other hand, although a lot of effort has been done in order to increase the throughput and minimum feature size of SPL, [116] optical lithography, particularly extreme UV lithography (EUVL), are far from being reached in terms of joint resolution and large scale production when deal-ing with electronic devices.…”

Photo-processing of perovskites: current research status and challenges

“…In situ photopatterning CsPbI 3 perovskite NCs was also achieved by using pulsed lasers, such as 405 or 1064 nm nanosecond laser 68,69 and high repetition 800 nm femtosecond laser 70,71 . The PL quantum yield reaches 92% and the obtained minimum line width is 0.9 μm 68 .…”

“…In situ photopatterning CsPbI 3 perovskite NCs was also achieved by using pulsed lasers, such as 405 or 1064 nm nanosecond laser 68,69 and high repetition 800 nm femtosecond laser 70,71 . The PL quantum yield reaches 92% and the obtained minimum line width is 0.9 μm 68 . Compared with the thermal annealing route, nanosecond laser can generate higher compacted perovskite films with larger crystal size (Fig.…”

“…As aforementioned, photo-processing, typically the laser direct writing, allows for creating the perovskite patterns with the dot size down to several micrometers, which hold great potential in the applications of optical storage and encryption 42,45,68,83,95,129 . Especially, 3D (X, Y, Z position in space) optical storage is possible based on ultrafast laser direct writing in the glass 33,75,76,130 .…”

Recent Advances of Solid Additives Used in Organic Solar Cells: Toward Efficient and Stable Solar Cells

“…Organic photovoltaics (OPVs), which convert solar energy into electric energy, have broad application prospects due to low cost, good flexibility, and ease of large-area preparation. − Benefiting from the development of conjugated molecules and optimization of active layer morphology, − the power conversion efficiency (PCE) of state-of-art single-junction OPVs has exceeded 19% for bulk heterojunction (BHJ) structures . However, the performance of OPVs still falls behind that of perovskite- or silicon-based solar cells. − Therefore, further improving PCE is the primary aim of OPV research.…”