Search

Low‐temperature, ambient processing of high‐quality CsPbBr3 films is demanded for scalable production of efficient, low‐cost carbon‐electrode perovskite solar cells (PSCs). Herein, we demonstrate a crystal orientation engineering strategy of PbBr2 precursor film to accelerate its reaction with CsBr precursor during two‐step sequential deposition of CsPbBr3 films. Such a novel strategy is proceeded by adding CsBr species into PbBr2 precursor, which can tailor the preferred crystal orientation of PbBr2 film from [020] into [031], with CsBr additive staying in the film as CsPb2Br5 phase. Theoretical calculations show that the reaction energy barrier of (031) planes of PbBr2 with CsBr is lower about 2.28 eV than that of (020) planes. Therefore, CsPbBr3 films with full coverage, high purity, high crystallinity, micro‐sized grains can be obtained at a low temperature of 150 °C. Carbon‐electrode PSCs with these desired CsPbBr3 films yield the record‐high efficiency of 10.27% coupled with excellent operation stability. Meanwhile, the 1 cm2 area one with the superior efficiency of 8.00% as well as the flexible one with the champion efficiency of 8.27% and excellent mechanical bending characteristics are also achieved. [ABSTRACT FROM AUTHOR]

All‐inorganic perovskite CsPbI2Br is emerging as a promising absorber material for perovskite solar cells (PSCs) due to its superior photophysical properties and thermal stability. However, there are still many great challenges to obtaining high‐quality, phase‐stable, thick CsPbI2Br films in ambient air to promote further development of the PSCs. Herein, for the first time, an intermediate phase‐assisted sequential deposition for desired CsPbI2Br films is proposed. It is carried out by sequentially spin‐coating PbBr2 and CsI precursors onto the substrate in ambient air, during which a Ruddlesden–Popper (R–P) perovskite intermediate phase film composed of a Cs‐Pb‐I‐Br complex is produced. After annealing, the intermediate phase film is transformed into a CsPbI2Br film consisting of CsPbI2Br grains and CsBr species through a spinodal decomposition reaction. The as‐obtained CsPbI2Br film holds full coverage, micro‐sized grains, and excellent phase stability. Moreover, the CsBr species located at grain boundaries can effectively passivate the defects. Therefore, a carbon‐electrode PSC with such a desired CsPbI2Br film yields the optimized efficiency of 15.24%, coupled with a remarkable photovoltage of 1.312 V and excellent stability in ambient air with relative humidity of 60–70%. The efficiency achieved herein is among the record efficiencies for carbon‐electrode PSCs based on various all‐inorganic perovskites reported currently. [ABSTRACT FROM AUTHOR]

Highlights: A novel interface design of producing interfacial voids is proposed for CsPbIBr2 perovskite solar cells (PSCs), which is free of any extra modification layer. Interfacial voids improve absorption of CsPbIBr2 film, reduce saturation current density, and enlarge built-in potential of the PSCs. The PSC yields a superior efficiency of 10.20% with a record-high photovoltage of 1.338 V.A novel interface design is proposed for carbon-based, all-inorganic CsPbIBr2 perovskite solar cells (PSCs) by introducing interfacial voids between TiO2 electron transport layer and CsPbIBr2 absorber. Compared with the general interfacial engineering strategies, this design exempts any extra modification layer in final PSC. More importantly, the interfacial voids produced by thermal decomposition of 2-phenylethylammonium iodide trigger three beneficial effects. First, they promote the light scattering in CsPbIBr2 film and thereby boost absorption ability of the resulting CsPbIBr2 PSCs. Second, they suppress recombination of charge carriers and thus reduce dark saturation current density (J0) of the PSCs. Third, interfacial voids enlarge built-in potential (Vbi) of the PSCs, awarding increased driving force for dissociating photo-generated charge carriers. Consequently, the PSC yields the optimized efficiency of 10.20% coupled with an open-circuit voltage (Voc) of 1.338 V. The Voc achieved herein represents the best value among CsPbIBr2 PSCs reported earlier. Meanwhile, the non-encapsulated PSCs exhibit an excellent stability against light, thermal, and humidity stresses, since it remains ~ 97% or ~ 94% of its initial efficiency after being heated at 85 °C for 12 h or stored in ambient atmosphere with relative humidity of 30–40% for 60 days, respectively. [ABSTRACT FROM AUTHOR]

Perovskite CsPbIBr2 is attracting ever‐increasing attention for carbon‐based, all‐inorganic solar cells, owing to its well‐balanced band gap and stability features. However, significant interfacial recombination of charge carriers in solar cells fabricated with this active layer, which is intrinsically associated with the unwanted conduction band misalignment between CsPbIBr2 and the commonly used TiO2 electron transport layer, has limited power conversion efficiency (PCE) values. Herein, we demonstrate successful conduction band alignment engineering at the TiO2/CsPbIBr2 heterojunction by modifying TiO2 with CsBr clusters. Such modification triggers a beneficial increase in the conduction band minimum (CBM) of TiO2 from −4.00 to −3.81 eV and decreases the work function from 4.11 to 3.86 eV, thus promoting favorable band alignment at the heterojunction, suppressing recombination, and improving extraction and transport of charge carriers. As a result, the carbon‐based, all‐inorganic CsPbIBr2 solar cells exhibit over 20 % enhancement in average PCE. The champion device achieves a PCE of 10.71 %, a record among pure CsPbIBr2‐based cells, open‐circuit voltage of 1.261 V, and excellent stability. [ABSTRACT FROM AUTHOR]

All-inorganic carbon-based CsPbIBr2 perovskite solar cells (PSCs) have attracted increasing interest due to the low cost and the balance between bandgap and stability. However, the relatively narrow light absorption range (300 to 600 nm) limited the further improvement of short-circuit current density (JSC) and power conversion efficiency (PCE) of PSCs. Considering the inevitable reflectance loss (~10%) at air/glass interface, we prepared the moth-eye anti-reflector by ultraviolet nanoimprint technology and achieved an average reflectance as low as 5.15%. By attaching the anti-reflector on the glass side of PSCs, the JSC was promoted by 9.4% from 10.89 mA/cm2 to 11.91 mA/cm2, which is the highest among PSCs with a structure of glass/FTO/c-TiO2/CsPbIBr2/Carbon, and the PCE was enhanced by 9.9% from 9.17% to 10.08%. The results demonstrated that the larger JSC induced by the optical reflectance modulation of moth-eye anti-reflector was responsible for the improved PCE. Simultaneously, this moth-eye anti-reflector can withstand a high temperature up to 200 °C, and perform efficiently at a wide range of incident angles from 40° to 90° and under various light intensities. This work is helpful to further improve the performance of CsPbIBr2 PSCs by optical modulation and boost the possible application of wide-range-wavelength anti-reflector in single and multi-junction solar cells. [ABSTRACT FROM AUTHOR]

Commercial SnO 2 nanocrystals used for producing electron transporting layers (ETLs) of perovskite solar cells (PSC) are prone to aggregation at room temperature and contain many structural defects. Herein, we report that the LiOH additive can simultaneously delay the aggregation and donate the beneficial aging effect to SnO 2 nanocrystals. The resulting SnO 2 ETLs show the desired characteristics, including a broadened absorption range, reduced defects, improved transporting properties, and decreased work function. Meanwhile, perovskite Cs 0.15 FA 0.65 MA 0.20 Pb(I 0.80 Br 0.20 ) 3 films with a wide bandgap of 1.68 eV grown on them exhibit the pure phase, higher crystallinity, fewer defects, better buried-interface contact, and more aligned energy levels with each other than the ones based on SnO 2 nanocrystals without the LiOH additive and aging treatment. Hence, the average efficiencies are boosted from (18.79 ± 0.40)% to (20.16 ± 0.36)% for the resulting wide-bandgap PSCs, wherein the champion efficiency of 21.12% is achieved. In addition, the as-obtained PSCs possess good thermal and humidity stability.

All-inorganic perovskite CsPbIBr 2 materials are promising for optoelectronics, owing to their upgraded ambient stability and suitable bandgap. Unfortunately, they generally undergo severe halide phase segregation under illumination, which creates many iodide-rich and bromide-rich domains coupled with significant deterioration of their optical/electrical properties. Herein, we propose a facile and effective strategy to overcome the halide phase segregation in the CsPbIBr 2 film by modifying its crystalline grains with poly(methyl methacrylate) (PMMA) for the first time. Such a strategy is proceeded by covering a PMMA layer on the substrate before deposition of the CsPbIBr 2 film. Further investigations manifest that the CsPbIBr 2 film with PMMA possesses larger grains, better crystallinity, and fewer traps than the one without any modification. Moreover, it holds the nearly eliminated halide phase segregation. Therefore, the carbon-based, all-inorganic CsPbIBr 2 perovskite solar cell exhibits the much suppressed photocurrent hysteresis, coupled with an outstanding efficiency of 9.21% and a high photovoltage of 1.307 V.

All-inorganic, Cl-based perovskites are promising for visible-blind UV photodetectors (PDs), particularly the self-powered ones. However, the devices are rarely reported until now since the low solubility of raw materials hinders significantly the thickness and electronic quality of solution-processed Cl-based perovskite films. Herein, we demonstrate a simple intermediate phase halide exchange method to prepare desired dual-phase CsPbCl 3 -Cs 4 PbCl 6 films. It is achieved by spin-coating of a certain dose of CH 3 NH 3 Cl/CsCl solution onto a CsI-PbBr 2 -dimethyl sulfoxide (DMSO) intermediate phase film, followed by thermal annealing. The inclusion of CsCl species in the solution is crucial to a stable dual-phase CsPbCl 3 -Cs 4 PbCl 6 film, while a high annealing temperature contributes to improving its quality. Therefore, the dual-phase CsPbCl 3 -Cs 4 PbCl 6 film with an absorption onset of ∼420 nm, microsized grains, a few defects, and a proper work function is obtained by optimizing the annealing temperature. The final self-powered, visible-blind UV PD exhibits the superior performance, including a favored response range of 310-420 nm, a high responsivity ( R ) peak value of 61.8 mA W -1 , an exceptional specific detectivity ( D *) maximum of 1.35 × 10 12 Jones, and a particularly fast response speed of 2.1/5.3 μs, together with amazing operational stability. This work represents the first demonstration of solution-processed, self-powered, visible-blind UV PDs with all-inorganic, Cl-based perovskite films.

Carbon-based, all-inorganic perovskite solar cells (PSCs) have drawn enormous attention recently on account of their ungraded stability and reduced costs. However, their power conversion efficiencies (PCEs) still lag behind the ones with conventional architecture. Moreover, the high cost of FTO substrates and energy-consuming sintering process of TiO 2 electron-transporting layers should be further addressed. Herein, it is demonstrated that the FTO/TiO 2 substrates could be separated simply from degraded CsPbIBr 2 PSCs for fabricating the new ones again, which thus reduces the production costs of resulting PSCs and makes them renewable and sustainable. Meanwhile, the characterization results reveal that there are some residual CsPbIBr 2 -derived species on recycled FTO/TiO 2 substrates, which enable the upper CsPbIBr 2 films with suppressed halide phase separation and reduced defects, the diminished work function of TiO 2 layers from 4.13 to 3.89 eV, along with decreased conduction band minimum (CBM) difference of CsPbIBr 2 /TiO 2 interface from 0.51 to 0.36 eV. Consequently, the average PCE of CsPbIBr 2 PSCs is improved by 20%, from 6.51 ± 0.62% to 8.14 ± 0.63%, wherein the champion one yields the exceptional value of 9.12%. These findings provide an avenue for simultaneous performance enhancement and cost-saving of carbon-based, all-inorganic PSCs to promote their commercialization.