Recent Progress of Wide Bandgap Perovskites towards Two-Terminal Perovskite/Silicon Tandem Solar Cells.

Perovskite/silicon tandem solar cells have garnered considerable interest due to their potential to surpass the Shockley-Queisser limit of single-junction Si solar cells. The rapidly advanced efficiencies of perovskite/silicon tandem solar cells benefit from the significant improvements in perovskite technology. Beginning with the evolution of wide bandgap perovskite cells towards two-terminal (2T) perovskite/silicon tandem solar cells, this work concentrates on component engineering, additives, and interface modification of wide bandgap perovskite cells. Furthermore, the advancements in 2T perovskite/silicon tandem solar cells are presented, and the influence of the central interconnect layer and the Si cell on the progression of the tandem solar cells is emphasized. Finally, we discuss the challenges and obstacles associated with 2T perovskite/silicon tandem solar cells, conducting a thorough analysis and providing a prospect for their future.

Graded Heterojunction Improves Wide-Bandgap Perovskite for Highly Efficient 4-Terminal Perovskite/Silicon Tandem Solar Cells.

Wide-bandgap (WBG) perovskite solar cells (PSCs) are essential for highly efficient and stable silicon/perovskite tandem solar cells. In this study, we adopted a synthetic strategy with lead thiocyanate (Pb(SCN)2) additive and methylammonium chloride (MACl) posttreatment to enhance the crystallinity and improve the interface of WBG perovskite films with a bandgap of 1.68 eV. The excessive PbI2 was formed at grain boundaries and converted into MAPbI3-xClx perovskites, which are utilized to form the graded heterojunction (GHJ) and compressive strain. This is beneficial for passivating nonradiative recombination defects, suppressing halide phase segregation, and facilitating carrier extraction. Subsequently, the device with GHJ delivered a champion efficiency of 20.30% and superior stability in ambient air and under 85 °C. Finally, we achieved a recorded efficiency of 30.91% for 4-terminal WBG perovskite/TOPCon tandem silicon solar cells. Our findings demonstrate a promising approach for fabricating efficient and stable WBG PSCs through the formation of GHJ.

Interfacial Dipole poly(2-ethyl-2-oxazoline) Modification Triggers Simultaneous Band Alignment and Passivation for Air-Stable Perovskite Solar Cells.

To promote the performance of perovskite solar cells (PSCs), its theoretical power conversion efficiency (PCE) and high stability, elaborative defect passivation, and interfacial engineering at the molecular level are required to regulate the optoelectric properties and charge transporting process at the perovskite/hole transport layer (HTL) interfaces. Herein, we introduce for the first time a multifunctional dipole polymer poly(2-ethyl-2-oxazoline) (PEOz) between the perovskite and Spiro-OMeTAD HTL in planar n-i-p PSCs, which advances the PSCs toward both high efficiency and excellent stability by stimulating three beneficial effects. First, the ether-oxygen unshared electron pairs in PEOz chemically react with unsaturated Pb2+ on the perovskite surfaces by forming a strong Pb-O bond, which effectively reduces the uncoordinated defects on the perovskite surfaces and enhances the absorption ability of the resulting PSCs. Second, the dipole induced by PEOz at the perovskite/HTL interface can decrease the HOMO and LUMO level of Spiro-OMeTAD and optimize the band alignment between these layers, thereby suppressing the interfacial recombination and accelerating the hole transport/extraction ability in the cell. Third, the hygroscopic PEOz thin film can protect perovskite film from water erosion by absorbing the water molecules before perovskite does. Finally, the PEOz-modified PSC exhibits an optimized PCE of 21.86%, with a high short-circuit current density (Jsc) of 24.88 mA/cm2, a fill factor (FF) of 0.79, and an open-circuit voltage (Voc) of 1.11 V. The unencapsulated devices also deliver excellent operation stability over 300 h in an ambient atmosphere with a humidity of 30~40% and more than 10 h under thermal stress.

Stability Improvement of Perovskite Solar Cells by the Moisture-Resistant PMMA:Spiro-OMeTAD Hole Transport Layer.

Perovskite solar cells (PSCs) based on the 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD) hole transport layer have exhibited leading device performance. However, the instability caused by this organic function layer is a very important limiting factor to the further development of PSCs. In this work, the spiro-OMeTAD is doped with polymethyl methacrylate (PMMA), which is further used as the hole transport layer to improve the device stability. It is shown that the PMMA can effectively improve the moisture and oxygen resistance of spiro-OMeTAD, which leads to improved device stability by separating the perovskite layer from moisture and oxygen. The device efficiency can maintain 77% of the original value for PSCs with the PMMA-doped spiro-OMeTAD hole transport layer, under a natural air environment (RH = 40%) for more than 80 days. The results show that the moisture- and oxygen-resistant PMMA:spiro-OMeTAD hole transport layer is effective at improving the device performance.

Optimization of Sacrificial Layer Etching in Single-Crystal Silicon Nano-Films Transfer Printing for Heterogeneous Integration Application.

As one of the important technologies in the field of heterogeneous integration, transfer technology has broad application prospects and unique technical advantages. This transfer technology includes the wet chemical etching of a sacrificial layer, such that silicon nano-film devices are released from the donor substrate and can be transferred. However, in the process of wet etching the SiO2 sacrificial layer present underneath the single-crystal silicon nano-film by using the transfer technology, the etching is often incomplete, which seriously affects the efficiency and quality of the transfer and makes the device preparation impossible. This article analyzes the principle of incomplete etching, and compares the four factors that affect the etching process, including the size of Si nano-film on top of the sacrificial layer, the location of the anchor point, the shape of Si nano-film on top of the sacrificial layer, and the thickness of the sacrificial layer. Finally, the etching conditions are obtained to avoid the phenomenon of incomplete etching of the sacrificial layer, so that the transfer technology can be better applied in the field of heterogeneous integration. Additionally, Si MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors) on sapphire substrate were fabricated by using the optimized transfer technology.

Generic water-based spray-assisted growth for scalable high-efficiency carbon-electrode all-inorganic perovskite solar cells.

A water-based spray-assisted growth strategy is proposed to prepare large-area all-inorganic perovskite films for perovskite solar cells (PSCs), which involves in spraying of cesium halide water solution onto spin-coating-deposited lead halide films, followed by thermal annealing. With CsPbBr3 as an example, we show that as-proposed growth strategy can enable the films with uniform surface, full coverage, pure phase, large grains, and high crystallinity, which primarily benefits from the controllable CsBr loading quantity, and the use of water as CsBr solvent makes the reaction between CsBr and PbBr2 immune to PbBr2 film microstructure. As a result, the small-area (0.09 cm2) and large-area (1.00 cm2) carbon-electrode CsPbBr3 PSCs yield the record-high efficiencies of 10.22% and 8.21%, respectively, coupled with excellent operational stability. We also illustrate that the water-based spray-assisted deposition strategy is suitable to prepare CsPbCl3, CsPbIBr2, and CsPbI2Br films with outstanding efficiencies of 1.27%, 10.44%, and 13.30%, respectively, for carbon-electrode PSCs.

Performance Enhancement of All-Inorganic Carbon-Based CsPbIBr2 Perovskite Solar Cells Using a Moth-Eye Anti-Reflector.

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.

Synchronous Interface Modification and Bulk Passivation via a One-Step Cesium Bromide Diffusion Process for Highly Efficient Perovskite Solar Cells.

Perovskite film modification is one of the most effective methods to improve the performance of perovskite solar cells. The modification should follow its characters of an asymmetric structure and the corresponding charge transportation and extraction. In this work, it is shown that synchronous interface modification and bulk passivation for highly efficient PSCs can be achieved by a one-step cesium bromide (CsBr) diffusion process because it is more suitable for an asymmetric structure. The synchronous interface modification and bulk asymmetric passivation can be better applied to the asymmetric PSC structure and can boost the power conversion efficiency apparently from 19.5 to 22.1%. It is shown that the perovskite crystallization is improved and the charge extraction is also enhanced obviously due to the better band alignment matching. The diffusion of CsBr into the perovskite bulk could form a gradient distribution, which is more applicable to the asymmetric charge transport and extraction. Thus, the CsBr at the interface between the electronic transport layer (ETL) and perovskite, as well as in the perovskite bulk, could suppress charge recombination. All of these factors can improve the JSC and VOC as well as the power conversion efficiency (PCE) of the PSCs. The results point out that the studied method is a simple and efficient way to fabricate high-performance PSCs by interface modification and bulk asymmetric passivation in a single step.

Suppressing Halide Phase Segregation in CsPbIBr2 Films by Polymer Modification for Hysteresis-Less All-Inorganic Perovskite Solar Cells.

All-inorganic perovskite CsPbIBr2 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 CsPbIBr2 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 CsPbIBr2 film. Further investigations manifest that the CsPbIBr2 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 CsPbIBr2 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.

Ultrawide Band Gap Oxide Semiconductor-Triggered Performance Improvement of Perovskite Solar Cells via the Novel Ga2O3/SnO2 Composite Electron-Transporting Bilayer.

The performance of perovskite solar cells (PSCs), especially for the parameters of open-circuit voltage (Voc) and fill factor, is seriously restricted by the unavoidable interfacial charge recombination. In this study, an ultrawide band gap semiconductor material of Ga2O3 is introduced between fluorine-doped tin oxide and SnO2 to regulate the interfacial charge dynamics by forming the Ga2O3/SnO2 electron-transporting bilayer. Ga2O3 has an appropriate conduction band minimum which benefits the electron transport, and at the same time, it has a very deep valence band maximum which could be regarded as an effective blocking layer. Such an innovative structure triggers the advantages of a lower work function and a smoother surface of the electron-transporting bilayer which leads to a high-quality perovskite film. Furthermore, superior hole-blocking properties of the introduced Ga2O3 layer could effectively reduce the interfacial recombination. All the properties could help to improve the extracting and transporting ability of charge carriers synergistically. Finally, the efficiency and stability of PSCs are greatly enhanced. All results suggest that the performance of PSCs could be improved effectively by introducing the ultrawide band gap oxide semiconductor of Ga2O3.

Charge-Transporting-Layer-Free, Vacuum-Free, All-Inorganic CsPbIBr2 Perovskite Solar Cells Via Dipoles-Adjusted Interface.

The inorganic perovskite has a better stability than the hybrid halide perovskite, and at the same time it has the potential to achieve an excellent photoelectric performance as the organic-inorganic hybrid halide perovskite. Thus, the pursuit of a low-cost and high-performance inorganic perovskite solar cell (PSC) is becoming the research hot point in the research field of perovskite devices. In setting out to build vacuum-free and carbon-based all-inorganic PSCs with the traits of simple fabrication and low cost, we propose the ones with a simplified vertical structure of FTO/CsPbIBr2/carbon upon interfacial modification with PEI species. In this structure, both the electron-transporting-layer and hole-transporting-layer are abandoned, and the noble metal is also replaced by the carbon paste. At the same time, FTO is modified by PEI, which brings dipoles to decrease the work function of FTO. Through our measurements, the carrier recombination has been partially suppressed, and the performance of champion PSCs has far exceeded the control devices without PEI modification, which yields a power conversion efficiency of 4.9% with an open circuit voltage of 0.9 V and a fill factor of 50.4%. Our work contributes significantly to give an available method to explore charge-transporting-layer-free, low-cost, and high-performance PSCs.

Dual-Phase CsPbCl3-Cs4PbCl6 Perovskite Films for Self-Powered, Visible-Blind UV Photodetectors with Fast Response.

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 CsPbCl3-Cs4PbCl6 films. It is achieved by spin-coating of a certain dose of CH3NH3Cl/CsCl solution onto a CsI-PbBr2-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 CsPbCl3-Cs4PbCl6 film, while a high annealing temperature contributes to improving its quality. Therefore, the dual-phase CsPbCl3-Cs4PbCl6 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 × 1012 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.

Transparent Ultrathin Metal Electrode with Microcavity Configuration for Highly Efficient TCO-Free Perovskite Solar Cells.

Optical microcavity configuration is one optical strategy to enhance light trapping in devices using planar electrodes. In this work, the potential application of optical microcavity configuration with ultrathin metal electrodes in highly efficient perovskite solar cells (PSCs) was investigated. By comparing with the device with conventional indium-tin-oxide (ITO) electrodes, it is shown that by carefully designing the Ag/dielectric planar electrode, a device with an optical microcavity structure can achieve comparable-or even higher-power conversion efficiency than a conventional device. Moreover, there is a relative high tolerance for the Ag film thickness in the optical microcavity structure. When the thickness of the Ag film is increased from 8 to 12 nm, the device still can attain the performance level of a conventional device. This gives a process tolerance to fabricate devices with an optical microcavity structure and reduces process difficulty. This work indicates the great application potential of optical microcavities with ultrathin metal electrodes in PSCs; more research attention should be paid in this field.

Highly efficient bifacial CsPbIBr2 solar cells with a TeO2/Ag transparent electrode and unsymmetrical carrier transport behavior.

Bright red CsPbIBr2 films possess intrinsic semitransparent features, which make them promising materials for smart photovoltaic windows, power plants, curtain walls, top cells for tandem solar cells, and bifacial photovoltaics. In this work, bifacial CsPbIBr2 perovskite solar cells (PSCs) have been fabricated by adopting an ultrathin silver (Ag) film transparent anode and a tellurium oxide (TeO2) optical modifying layer. The results showed that the transmittance of the TeO2 (40 nm)/Ag (11 nm) transparent top anode matched well with the light absorption range of the CsPbIBr2 film, and the resulting bifacial PSCs exhibited PCEs of 8.04% and 5.32% when illuminated from the FTO and Ag sides, respectively. By introducing cesium iodide-treated CsPbIBr2 layers, the PSCs achieved superior PCEs of 8.46% (FTO side) and 6.40% (Ag side) with a bifacial factor of 75.65%, which is the best performance of bifacial CsPbIBr2 PSCs reported to date. Interestingly, an identical cell showed a significantly higher fill factor, more efficient carrier transport, and better efficiency and stability when illuminated from the Ag side than from the FTO side, a phenomenon strongly related to the parasitic absorption of the spiro-OMeTAD layer below 420 nm. Consequently, we have found a route similar to "shooting fish in a barrel" to enhance the carrier transport, suppress the carrier recombination, and improve the stability of bifacial semitransparent CsPbIBr2 PSCs: turning the Ag side towards the sun.

Recycling of FTO/TiO2 Substrates: Route toward Simultaneously High-Performance and Cost-Efficient Carbon-Based, All-Inorganic CsPbIBr2 Solar Cells.

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 TiO2 electron-transporting layers should be further addressed. Herein, it is demonstrated that the FTO/TiO2 substrates could be separated simply from degraded CsPbIBr2 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 CsPbIBr2-derived species on recycled FTO/TiO2 substrates, which enable the upper CsPbIBr2 films with suppressed halide phase separation and reduced defects, the diminished work function of TiO2 layers from 4.13 to 3.89 eV, along with decreased conduction band minimum (CBM) difference of CsPbIBr2/TiO2 interface from 0.51 to 0.36 eV. Consequently, the average PCE of CsPbIBr2 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.

Interfacial Voids Trigger Carbon-Based, All-Inorganic CsPbIBr2 Perovskite Solar Cells with Photovoltage Exceeding 1.33 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.

High-performance Acetone Soluble Tape Transfer Printing Method for Heterogeneous Integration.

A high-performance transfer printing method using a new soluble tape which can be dissolved in acetone is proposed to be used in heterogeneous integration. Si inks array was transferred from SOI wafers onto various substrates without adhesion promoter by this new method which we refer to as the acetone soluble tape (AST) method to compare with other transfer printing methods by using thermal release tape (TRT), water soluble tape (WST) and polydimethylsiloxane (PDMS). By using the AST method, the transfer printing process does not involve interface contention between stamp/inks and inks/receiver substrate so that it maximizes the transfer printing efficiency. Experimental results present the AST method has good performances, and various alien substrates, even curvilinear surfaces, can be selected as receiver substrates by the AST method. To examine the quality of the transferred Si inks, the Si TFTs were fabricated by using the Si membrane transferred by the AST method on sapphire substrate and the devices show the good performance. All the results confirm that the AST method is an effective method in heterogeneous integration.

Influence of Carrier Gases on the Quality of Epitaxial Corundum-Structured α-Ga2O3 Films Grown by Mist Chemical Vapor Deposition Method.

This report systematically investigates the influence of different carrier gases (O2, N2, and air) on the growth of gallium oxide (Ga2O3) thin films on c-plane sapphire substrates by using the mist-CVD method. Although XRD and Raman measurements show that the pure corundum-structured α-Ga2O3 with single (0006) plane orientation was successfully obtained for all three different carrier gases, the crystal quality could be greatly affected by the carrier gas. When O2 is used as the carrier gas, the smallest full-width at half maximum (FWHM), the very sharp absorption cutoff edge, the perfect lattice structure, the highest growth rate, and the smooth surface can be obtained for the epitaxial α-Ga2O3 film as demonstrated by XRD, UV-VIS, TEM, AFM (Atomic Force Microscope), and SEM measurements. It is proposed that the oxygen content in carrier gas should be responsible for all of these results. XPS (X-ray photoelectron spectroscopy) analysis also confirms that more oxygen elements can be included in epitaxial film when O2 is used as the carrier gas and thus help improve the crystal quality. The proper carrier gas is essential for the high quality α-Ga2O3 growth.

Efficient Ni/Au Mesh Transparent Electrodes for ITO-Free Planar Perovskite Solar Cells.

Indium thin oxide (ITO)-free planar perovskite solar cells (PSCs) were fabricated at a low temperature (150 °C) in this work based on the transparent electrode of photolithography processed nickel/gold (Ni/Au) mesh and the high conductivity polymer, PH1000. Ultrathin Au was introduced to increase the conductivity of metal mesh, and the optimal hexagonal Ni (30 nm)/Au (10 nm) mesh (line width of 5 µm) shows a transmittance close to 80% in the visible light region and a sheet resistance lower than 16.9 Ω/sq. The conductive polymer PH1000 not only smooths the raised surface of the metal mesh but also enhances the charge collection ability of metal mesh. The fabricated PSCs have the typical planar structure (glass/Ni-Au mesh/PH1000/PEDOT:PSS/MAyFA1-yPbIxCl3-x/PCBM/BCP/Ag) and the champion PSC (0.09 cm2) obtains a power conversion efficiency (PCE) of 13.88%, negligible current hysteresis, steady current density and PCE outputs, and good process repeatability. Its photovoltaic performance and stability are comparable to the reference PSC based on the ITO electrodes (PCE = 15.70%), which demonstrates that the Ni/Au mesh transparent electrodes are a promising ITO alternative to fabricate efficient PSCs. The relatively lower performance of Ni/Au based PSC results from the relatively slower charge extraction and stronger charge recombination than the ITO based PSC. Further, we tried to fabricate the large area (1 cm2) device and achieve a PCE over 6% with negligible hysteresis and steady current density and PCE outputs. The improvements of perovskite film quality and interface modification should be an effective approach to further enhance the device performance of Ni/Au based PSCs, and the Ni/Au mesh electrode may find wider applications in PSCs and flexible devices.

Intermediate Phase Halide Exchange Strategy toward a High-Quality, Thick CsPbBr3 Film for Optoelectronic Applications.

Inorganic halide perovskite CsPbBr3 is emerging as one of the promising alternatives to the hybrid counterparts for optoelectronic applications owing to its upgraded stability. Yet, the inherently low solubility of a CsBr precursor material restricts the quality and especially the thickness of a solution-processed CsPbBr3 film, thus hindering the further optimization of device performance. Herein, we report a facile intermediate phase halide exchange reaction that can break the thickness limit of a solution-processed CsPbBr3 film, since it avoids the use of low-solubility CsBr. Furthermore, the CH3NH3I byproduct after halide exchange could trigger a beneficial Ostwald ripening process to promote grain coarsening in the film. Hence, the uniformly flat, pure-phase, and compact CsPbBr3 film composed of [100] preferential, microsized grains can be achieved. As a demonstration of its excellent optoelectronic features, the carbon-based, all-inorganic photodetector with such a favorable film yields a maximum photoresponsivity of 0.35 A W-1 and a specific detectivity of 1.94 × 1013 Jones coupled with a response time of 0.58 µs.