Additive Engineering in Antisolvent for Widening the Processing Window and Promoting Perovskite Seed Formation in Perovskite Solar Cells

Slow-Release Effect Assisted Crystallization for Sequential Deposition Realizes Efficient Inverted Perovskite Solar Cells

The two-step sequential deposition strategy has been widely recognized in promoting the research and application of perovskite solar cells, but the rapid reaction of organic salts with lead iodide inevitably affects the growth of perovskite crystals, accompanied by the generation of more defects. In this study, the regulation of crystal growth was achieved in a two-step deposition method by mixing 1-naphthylmethylammonium bromide (NMABr) with organic salts. The results show that the addition of NMABr effectively delays the aggregation and crystallization behavior of organic salts; thereby, the growth of the optimal crystal (001) orientation of perovskite is promoted. Based on this phenomenon of delaying the crystallization process of perovskite, the "slow-release effect assisted crystallization" is defined. Moreover, the incorporation of the Br element expands the band gap of perovskite and mitigates material defects as nonradiative recombination centers. Consequently, the power conversion efficiency (PCE) of the enhanced perovskite solar cells (PSCs) reaches 20.20%. It is noteworthy that the hydrophobic nature of the naphthalene moiety in NMABr can enhance the humidity resistance of PSCs, and the perovskite phase does not decompose for more than 3000 h (30-40% RH), enabling it to retain 90% of its initial efficiency even after exposure to a nitrogen environment for 1200 h.

Flexible p-i-n perovskite solar cell with optimized performance by KBF4 additive

Flexible perovskite solar cells (F-PSCs) prevail in the clean energy field for their light weight, easy fabrication and installation, but the power conversion efficiency of F-PSCs needs further improvement. In this work, we numerically simulate and experimentally demonstrate the effect of the perovskite trap defects density on the power conversion efficiency. The pseudo-halide KBF4 is employed as the additive to passivate the trap defects in the perovskite films. The high electrophilicity of BF4 - group ensures its entering into perovskite lattice, optimizing crystallinity and improving the qualities of perovskite films, K+ ions can effectively passivate grain boundaries and inhibit halide anion migrations. After KBF4 passivation, trap defect density of the perovskite film was decreased from 8.0 × 1015cm-3 to 3.9 × 1015cm-3, and also the carrier lifetime increased from 108.52 ns to 234.72 ns. Consequently, the power conversion efficiency (PCE) of the F-PSCs devices increased from 13.99% to 16.04%.

Seeding Agents in Metal Halide Perovskite Solar Cells: From Material to Mechanism

Metal halide perovskite solar cells (PSCs) have been showing up in the commercial field, with an inspiring power conversion efficiency (PCE) of over 26 % in the laboratory. The quality of perovskite films is still a bottleneck due to the random and fast crystallization of ionic perovskite materials. Seeding agent-mediated crystallization has consistently been recognized as an efficient method for preparing bulk single crystals and high-quality films. Herein, we summarized the seeding mechanism, characterization techniques, and seeding agents working in different locations during PSC device fabrication. This Review could further facilitate researchers with a deeper understanding of seeding agents and enhance more choices for seeding crystallization to improve the performance further and the device's large-scale fabrication toward commercialization.

Antisolvent Additive Engineering for Boosting Performance and Stability of Graded Heterojunction Perovskite Solar Cells Using Amide-Functionalized Graphene Quantum Dots

Additive and antisolvent engineering strategies are outstandingly efficient in enhancing perovskite quality, photovoltaic performance, and stability of perovskite solar cells (PSCs). In this work, an effective approach is applied by coupling the antisolvent mixture and multi-functional additive procedures, which is recognized as antisolvent additive engineering (AAE). The graphene quantum dots functionalized with amide (AGQDs), which consists of carbonyl, amine, and long hydrophobic alkyl chain functional groups, are added to the antisolvent mixture of toluene (T) and hexane (H) as an efficient additive to form the CH₃NH₃PbI₃ (MAPI):AGQDs graded heterojunction structure. A broad range of analytical techniques, including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, space charge limited current, UV-visible spectroscopy, external quantum efficiency, and time-of-flight secondary ion mass spectrometry, are used to investigate the effect of AAE treatment with AGQDs on the quality of perovskite film and performance of the PSCs. Importantly, not only a uniform and dense perovskite film with hydrophobic property is obtained but also defects on the perovskite surface are significantly passivated by the interaction between AGQDs and uncoordinated Pb²⁺. As a result, an enhanced power conversion efficiency (PCE) of 19.10% is achieved for the champion PSCs treated with AGQD additive, compared to the PCE of 16.00% for untreated reference PSCs. In addition, the high-efficiency PSCs based on AGQDs show high stability and maintain 89% of their initial PCE after 960 h in ambient conditions.

Introduction of cadmium chloride additive to improve the performance and stability of perovskite solar cells

With the increase in the importance of using green energy sources to meet the world's energy demands, attempts have been made to push perovskite solar cell technology toward industrialization all around the world. Improving the properties of perovskite materials as the heart of PSCs is one of the methods to fabricate favorable photovoltaic (PV) solar cells based on perovskites. Here, cadmium chloride (CdCl₂) was used as an additive source for the perovskite precursor to improve its PV properties. Results indicated CdCl₂ improves the perovskite growth and tailors its crystalline properties, suggesting boosted charge transport processes in the bulk and interfaces of the perovskite layer with electron–hole transport layers. Overall, by incorporation of 1.0% into the MAPbI₃ layer, a maximum power conversion efficiency of 15.28% was recorded for perovskite-based solar cells, higher than the 12.17% for the control devices. The developed method not only improved the PV performance of devices but also boosted the stability behavior of solar cells due to the passivated domain boundaries and enhanced hydrophobicity in the CdCl₂-based devices.

With the increase in the importance of using green energy sources to meet the world's energy demands, attempts have been made to push perovskite solar cell technology toward industrialization all around the world.