Recent progress on low dimensional perovskite solar cells

Low dimensional perovskites have recently attracted much attention due to their vertical growth of crys- talline orientation, excellent film morphology, and long-term humidity, light, and heat stability, How- ever, low dimensional perovskites suffer fl＇om low power conversion efficiency （PCE） with respect to their three dimensional analogues. Therefore, it is imperative to find excellent low-dimensional perovskite materials for improving the PCE. Previous work has demonstrated that bulkier organic molecules, e,g., C6Hs（CH2）2NH3＋ （PEA＋）, CH3（CH2）3NH3＋（n-BAT, iso-BA＋）, C2H4NH3 ＋, and polyethylenimine cations （PEI＋）, play an important role in the formation of low-dimensional perovskites. In this review, we review the recent development of low dimensional perovskites for solar cells application in terms of film preparation, photophysics, and stability of perovskites, as well as the related device structure and physics. We have also discussed the future development of low-dimensional perovskites from materials design, fabri- cation processes, and device structure.

钙钛矿太阳能电池的发展现状和未来趋势

1.Introduction Carbon neutrality is an important strategy to address the acute problems of resource and environmental constraints.Currently,afforestation,energy conservation,emissions reduction,and other measures have been adopted to offset the total amount of carbon dioxide and other greenhouse gas emissions generated by countries,businesses,products,activities,or individuals,with the aim of finally achieving zero net emissions(Fig.1(a)).

Solution processed nano-ZnMgO interfacial layer for highly efficient inverted perovskite solar cells

Interfacial layer has a significant impact on the achievement of highly efficient organic–inorganic hybrid perovskite solar cells(PSCs). Here, we introduced a nano-ZnMgO(magnesium doped ZnO, abbreviated as ZnMgO) as interfacial layer between [6, 6]-Phenyl C_(61) butyric acid methyl ester(PC_(61) BM) layer and Al electrode to replace LiF or ZnO interlayer and enhance device performance. The device efficiency has been improved from 11.43% to 15.61% and the hysteresis was decreased dramatically. Such huge enhancement of power convert efficiency(PCE) can be attributed to the low dark current density, enhancement of electron-selective contact, and low energy barrier at the PC_(61) BM/Al interface. We suggest that this simple nano-scale interlayer can provide an efficient charge transport and extraction for highly efficient PSCs.

Chiral cation promoted interfacial charge extraction for efficient tin-based perovskite solar cells

Pb-free Sn-based perovskite solar cells(PSCs) have recently made inspiring progress, and power conversion efficiency(PCE) of 14.8% has been achieved. However, due to the energy-level mismatch and poor interfacial contact between commonly used hole transport layer(i.e., poly(3,4-ethylenedioxythio phene):poly(styrene sulfonate), PEDOT:PSS) and FASnI_(3) film, it is still challenging to effectively extract holes at the interface. Owing to the p-type nature of Sn-based perovskites, the efficient hole extraction is of particular significance to improve the PCE of their solar cells. In this work, for the first time, the role of chiral cations, a-methylbenzylamine(S-/R-/rac-MBA), in promoting hole transportation of FASnI_(3)-based PSCs is demonstrated. The introduction of MBAs is found to form 2D/3D film with lowdimensional structures locating at PEDOT:PSS/FASnI_(3) interface, which facilitates the energy level alignment and efficient charge transfer at the interface. Importantly, chiral-induced spin selectivity(CISS)effect of R-MBA_(2)SnI_(4)induced by chiral R-MBA cation is found to further assist the specific interfacial transport of accumulated holes. As a result, R-MBA-based PSCs achieve decent PCE of 10.73% with much suppressed hysteresis and enhanced device stability. This work opens up a new strategy to efficiently promote the interfacial extraction of accumulated charges in working PSCs.

Homogeneous permeation and oriented crystallization in nanostructured mesopores for efficient and stable printable mesoscopic perovskite solar cells

The low-cost and scalable printable mesoporous perovskite solar cells(p-MPSCs) face significant challenges in regulating perovskite crystal growth due to their nanoscale mesoporous scaffold structure, which limits the improvement of device power conversion efficiency(PCE). In particular, the most commonly used solvents, N,N-dimethylformamide(DMF) and dimethyl sulfoxide(DMSO), have a single chemical interaction with the precursor components and high volatility, which is insufficient to self-regulate the perovskite crystallization process, leading to explosive nucleation and limited growth within mesoporous scaffolds. Here, we report a mixed solvent system composed of methylamine formaldehyde(MAFa)-based ionic liquid and acetonitrile(ACN) with the strong C=O–Pb coordination and N–H···I hydrogen bonding with perovskite components. We found that the mixed solvent system is beneficial for the precursor solution to homogeneously penetrate into the mesoporous scaffold,and the strong C=O–Pb coordination and N–H···I hydrogen bonding interaction can promote the oriented growth of perovskite crystals. This synergistic effect increased the PCE of the p-MPSCs from 17.50% to 19.21%, which is one of the highest records for p-MPSC in recent years. Additionally, the devices exhibit positive environmental stability, retaining over 90% of the original PCE after 1,200 h of aging under AM 1.5 illumination conditions at 55 ℃ and 55% humidity.

Flexible, transparent nanocellulose paper-based perovskite solar cells

Recently perovskite solar cells(PSCs),as photoelectric conversion devices,exhibit excellent power conversion efficiency(PCE)and low-processing cost,and have become one of the most promising devices to replace conventional silicon-based solar cells and address current pressing energy issues.Among them,the flexible PSCs are especially more widely applicable and may propel the rapid advancements of wearable electronics,causing a significant paradigm shift in consumer electronics.Current flexible PSCs use non-biodegradable petroleum-based polymer substrates,discarding of which will aggravate“white pollution”.Therefore,development of green,biodegradable and low-cost flexible substrates will provide a great alternative to flexible PSCs.Here we have developed transparent nanocellulose paper(NCP)with coating of acrylic resin as substrates to fabricate flexible PSCs,which are biodegradable and easily disposable.The PCE of these NCP-based PSCs reached 4.25%,while the power per weight(the ratio of power to device weight)was as high as 0.56 W g^(–1).The flexible PSCs also showed good stability,retaining>80%of original efficiency after 50 times of bending.The NCP-based substrates can also be applied to other electronic systems,which may prosper next-generation green flexible electronics.

Origin of High Efficiency and Long-Term Stability in Ionic Liquid Perovskite Photovoltaic

Environment-friendly protic amine carboxylic acid ionic liquids(ILs)as solvents is a significant breakthrough with respect to traditional highly coordinating and toxic solvents in achieving efficient and stable perovskite solar cells(PSCs)with a simple one-step air processing and without an antisolvent treatment approach.However,it remains mysterious for the improved efficiency and stability of PSCs without any passivation strategy.Here,we unambiguously demonstrate that the three functions of solvents,additive,and passivation are present for protic amine carboxylic acid ILs.We found that the ILs have the capability to dissolve a series of perovskite precursors,induce oriented crystallization,and chemically passivate the grain boundaries.This is attributed to the unique molecular structure of ILs with carbonyl and amine groups,allowing for strong interaction with perovskite precursors by forming C=O…Pb chelate bonds and N-H…I hydrogen bonds in both solution and film.This finding is generic in nature with extension to a wide range of IL-based perovskite optoelectronics.

Ionic Liquid for Perovskite Solar Cells:An Emerging Solvent Engineering Technology

CONSPECTUS:Perovskite solar cells(PSCs)have,in recent years,become one of the most in-depth photovoltaic materials in many different disciplines due to their long-range charge carrier diffusion lengths,strong light absorption,easy tuning of the band gaps,low defect density,and solution processability.The power conversion efficiency(PCE)of single-junction PSCs has reached a certified value of 25.5%,which has caught up with or even surpassed traditional photovoltaic technologies,such as silicon(Si)solar cells,thin film solar cell,etc.In addition to the performance of PSCs comparable to traditional photovoltaic technology,its biggest feature is that it can be prepared by a solution method.The preparation process of the solution method simplify the film preparation process and greatly reduce the preparation cost.In addition,the solution method provides a favorable option for the energy supply of flexible wearable devices in the future.

Stable Metal–Halide Perovskite Colloids in Protic Ionic Liquid

Obtaining long-term stable and robust perovskite colloids solution remains an important scientific challenge due to the limited interaction between solvent and perovskite solutes.Here,we unveil the formation mechanism of chemically robust perovskite precursor solutions under ambient conditions using methylammonium acetate(CH3NH3•CH3COO,MAAc)protic ionic liquid(PIL)solvent.Tens of nanometers colloids are assembled on the molecular level via regular oriented gel-like lamellae with a mean thickness of 34.69 nm,width of 56.81 nm,and distance of 91.05 nm.

Correction to“Ionic Liquid for Perovskite Solar Cells:An Emerging Solvent Engineering Technology”

In the TOC and Conspectus graphics,“Perovskite Solar Cell”should be replaced by“Perovskite Solar Cells”and“Lonic liquid”should be replaced by“Ionic Liquid”.The corrected image is provided here.