Power Conversion Efficiency Of Device Research Articles

Work function tuning of directly grown graphene via ultraviolet–ozone treatment for electrode application in organic photovoltaic devices

Graphene is an efficient electrode material for flexible optoelectronic devices because of its high transmittance and electrical conductivity. A graphene film directly grown using plasma-enhanced chemical vapor deposition is suitable for electrode applications because it can be prepared on a glass substrate at relatively low temperatures without a transfer process from a metal catalyst. However, to obtain efficient optoelectronic devices using graphene electrodes, surface modification is necessary. Herein, we tuned the work function of a graphene electrode using ultraviolet (UV)-O3 treatment. The power conversion efficiency of organic photovoltaic devices was significantly increased by the UV-O3 treatment of the graphene anode. To investigate the origin of the improved device performance, the interface between the graphene anode and tetraphenyldibenzoperiflanthene (DBP) donor layer was analyzed via in situ ultraviolet photoelectron spectroscopy. The energy offset between the Fermi level of graphene and the highest occupied molecular orbital level of DBP was significantly reduced because of the increased work function. The results indicate that the electronic structure modification of graphene is of significant importance for fabricating efficient optoelectronic devices.

Organic Bromide Salts Interface Modification for High‐Efficiency Perovskite Solar Cells with Printed Carbon Electrode

Perovskite solar cells (PSCs) using carbon as the counter electrode fabricated through a low‐temperature full solution‐process method can significantly simplify the preparation process and reduce production cost. Herein, a high‐performance PSC is presented with printed carbon electrode and dopant‐free poly(3‐hexylthiophene) (P3HT) is employed as hole transport materials. Different organic bromide salts are employed to modify the perovskite/P3HT interface to further enhance the performance. As a result, methylammonium bromide (MABr) modification significantly enhances the device open‐voltage (Voc) and fill factor (FF) by reducing interface defects and facilitates charge transport. A champion power conversion efficiency (PCE) of 19.22% (Voc of 1.118 V, FF of 0.765, and short‐circuit current of 22.48 mA cm−2) is achieved with MABr modification. The unencapsulated devices maintain 96% of the initial efficiency after storage for 3600 h and 88% after thermal treatment at 70 °C for 1200 h. Additionally, perovskite solar modules are also prepared based on printing and interface passivation route with PCE reaches 13.20%. These results represent an important progress in the enhancement of device PCE and up‐scaling of PSCs with cost‐effective, stable, and printed carbon electrode.

Controlling photovoltaic performances of trifluoromethylated quinoxaline-based polymers via fluorine substitution

In this study, three D–A-type trifluoromethylated quinoxaline-based polymers, with different numbers of fluorine (F) atoms on the quinoxaline unit, were developed to clarify the impact of strongly electron-attracting F substituents on the photovoltaic characteristics of polymers. The unfluorinated reference quinoxaline-based polymer PTB-QxCF3, was prepared by coupling an alkylated benzodithiophene donor to a trifluoromethylated quinoxaline acceptor via a thiophene bridge. Subsequently, one and two fluorine atoms were attached to the vacant 6,7-positions of the trifluoromethylated quinoxaline unit to generate the fluorinated polymers PTB-FQxCF3 and PTB-2FQxCF3, respectively. An inverted-type polymer solar cell was constructed with Y6BO as a non-fullerene acceptor, to examine the photovoltaic characteristics of the polymers. Devices made from fluorinated PTB-FQxCF3 and PTB-2FQxCF3 exhibited higher power conversion efficiencies (PCEs) of 11.95% and 13.50%, respectively, than that comprising unfluorinated PTB-QxCF3 (4.80%). This noticeable advancement in the PCEs of devices with fluorinated polymers originates from the rapid increase in their photovoltaic parameters. These results demonstrate the usefulness of the fluorination strategy for promoting photovoltaic responses of trifluoromethylated quinoxaline-based polymers.

Tuning the Properties of Reduced Graphene Oxide-Sr0.7Sm0.3Fe0.4Co0.6O3 Nanocomposites as Potential Photoanodes for Dye-Sensitized Solar Cells

The generation of electricity using solar energy is an effective system to overcome the current global energy crisis. In this regard, developing new semiconductor materials can be of great interest in overcoming the challenge of charge carrier recombination and, hence, improving the power conversion efficiency (PCE) in photovoltaic devices, particularly dye-sensitized solar cells (DSSCs). Here, reduced graphene oxide-Sr0.7Sm0.3Fe0.6Co0.4O3 (RGO-SSFC) nanocomposites were synthesized using the hydrothermal method and characterized with the aid of microscopic and spectroscopic techniques, as well as a vibrating sample magnetometer, and further tested for application as photoanodes in DSSCs. Scanning electron microscopy revealed the presence of RGO nanosheets that were fully decorated by irregular- and spherical-shaped SSFC nanoparticles. Fourier-transform infrared spectroscopy confirmed the strong synergistic interaction of the RGO-SSFC nanocomposites. The large surface area of RGO-SSFC nanocomposite photoanodes facilitated effective dye loading, high photon absorption, and efficient electron transfer, resulting in better device performance. Compared to RGO-SSFC-0.1 and RGO-SSFC-1.0, the RGO-SSFC-0.5 nanocomposite showed an enhanced open-circuit voltage (Voc) of 0.84 V, short-circuit current density (Jsc) of 14.02 mA cm−2 , and a PCE of 7.25%. Eosin B and MK-2 organic dyes used as photosensitizers coated on the RGO-SSFC semiconductors resulted in low-cost DSSC photoanodes.Graphical

Conjugated small molecule inhibiting intrinsic ion migration and enriching electron transfer channels for stable and efficient perovskite solar cells

Generally, efficient and stable perovskite solar cells (PSCs) have the following characteristics: 1) less ion migration; 2) large perovskite grain size; 3) low defect state density; 4) efficient charge transfer and inhibited carrier recombination. Herein, this work reports a facile strategy of incorporating π-conjugated tetrafluoroterephthalonitrile (C8N2F4, abbreviated to CNF) into perovskite precursor solution for high-quality thin film. Surprisingly, the π-conjugated CNF molecule can realize the above characteristics at the same time. As a result, the champion PSC yields a power conversion efficiency (PCE) of 22.44% as well as a stabilized PCE of 21.77%. Further, the CNF-doped PSC (unencapsulated) retains 91.62% of its initial PCE after exposed to moist air (relative humidity: 50–80%) for 1500 h and shows excellent thermal stability (T80 > 1200 h) at 85 °C. The increased stability is due to the cation migration inhibition and the PbI (I site substitution by Pb) and IPb (Pb site substitution by I) defect passivation of perovskite after the incorporation of π-conjugated CNF molecule. Our results can deepen the understanding of organic small molecules for potential applications in improving the device PCE and the operation and long-term stability of PSC.

Adjusted Bulk and Interfacial Properties in Highly Stable Semitransparent Perovskite Solar Cells Fabricated by Thermocompression Bonding between Perovskite Layers.

In order to shield perovskite solar cells (PSCs) from extrinsic degradation factors and ensure long-term stability, effective encapsulation technology is indispensable. Here, a facile process is developed to create a glass-glass encapsulated semitransparent PSC using thermocompression bonding. From quantifying the interfacial adhesion energy and considering the power conversion efficiency of devices, it is confirmed that bonding between perovskite layers formed on a hole transport layer (HTL)/indium-doped tin oxide (ITO) glass and an electron transport layer (ETL)/ITO glass can offer an excellent lamination method. The PSCs fabricated through this process have only buried interfaces between the perovskite layer and both charge transport layers as the perovskite surface is transformed into bulk. The thermocompression process leads the perovskite to have larger grains and smoother, denser interfaces, thereby not only reducing defect and trap density but also suppressing ion migration and phase segregation under illumination. In addition, the laminated perovskite demonstrates enhanced stability against water. The self-encapsulated semitransparent PSCs with a wide-band-gap perovskite (Eg ∼ 1.67 eV) demonstrate a power conversion efficiency of 17.24% and maintain long-term stability with PCE > ∼90% in the 85 °C shelf test for over 3000 h and with PCE > ∼95% under AM 1.5 G, 1-sun illumination in an ambient atmosphere for over 600 h.

Magnetic Field-Assisted Interface Embedding Strategy to Construct 2D/3D Composite Structure for Stable Perovskite Solar Cells with Efficiency Over 24.

Perovskite solar cells (PSCs) based on 2D/3D composite structure have shown enormous potential to combine high efficiency of 3D perovskite with high stability of 2D perovskite. However, there are still substantial non-radiative losses produced from trap states at grain boundaries or on the surface of conventional 2D/3D composite structure perovskite film, which limits device performance and stability. In this work, a multifunctional magnetic field-assisted interfacial embedding strategy is developed to construct 2D/3D composite structure. The composite structure not only improves crystallinity and passivates defects of perovskite layer, but also can efficiently promote vertical hole transport and provide lateral barrier effect. Meanwhile, the composite structure also forms a good surface and internal encapsulation of 3D perovskite to inhibit water diffusion. As a result, the multifunctional effect effectively improves open-circuit voltage and fill factor, reaching maximum values of 1.246V and 81.36%, respectively, and finally achieves power conversion efficiency (PCE) of 24.21%. The unencapsulated devices also demonstrate highly improved long-term stability and humidity stability. Furthermore, an augmented performance of 21.23% is achieved, which is the highest PCE of flexible device based on 2D/3D composite perovskite films coupled with the best mechanical stability due to the 2D/3D alternating structure.

Co-evaporated p-i-n perovskite solar cells with sputtered NiOx hole transport layer

Metal oxides have long been used as charge transport layers in thin film solar cells due to their suitable energy band levels, high charge carrier mobilities, and excellent long-term stability. One example is non-stoichiometric nickel oxide (NiOx), a hole transport material which can be deposited in a conformal, scalable, and solvent-free manner via sputtering. However, sputtered NiOx has only ever been combined with spin-coated perovskite films in perovskite solar cells (PSCs). Here we report the fabrication of the first co-evaporated PSCs with sputtered NiOx as the hole transport layer. We reveal how the amount of argon gas used during sputtering affects important physical properties such as hole conductivity, visible light transmittance, and suitability of the NiOx surface for perovskite nucleation and growth. Optimized sputtering conditions led to CH3NH3PbI3 (MAPbI3) PSCs with an 18.6% power conversion efficiency (PCE), which was further increased to 19.5% by adding a spiro-TTB interlayer between NiOx and MAPbI3. We also show that removing the NiOx annealing step only reduced the device PCE by 1%, paving the way toward low-temperature deposition of metal oxide transport layers. This work exhibits the versatility of NiOx sputtering and perovskite evaporation as a powerful combination for solvent-free and low-temperature fabrication of highly efficient PSCs.

A Simple and Effective Phosphine-Doping Technique for Solution-Processed Nanocrystal Solar Cells.

Solution-processed cadmium telluride (CdTe) nanocrystal (NC) solar cells offer the advantages of low cost, low consumption of materials and large-scale production via a roll-to-roll manufacture process. Undecorated CdTe NC solar cells, however, tend to show inferior performance due to the abundant crystal boundaries within the active CdTe NC layer. The introduction of hole transport layer (HTL) is effective for promoting the performance of CdTe NC solar cells. Although high-performance CdTe NC solar cells have been realized by adopting organic HTLs, the contact resistance between active layer and the electrode is still a large problem due to the parasitic resistance of HTLs. Here, we developed a simple phosphine-doping technique via a solution process under ambient conditions using triphenylphosphine (TPP) as a phosphine source. This doping technique effectively promoted the power conversion efficiency (PCE) of devices to 5.41% and enabled the device to have extraordinary stability, showing a superior performance compared with the control device. Characterizations suggested that the introduction of the phosphine dopant led to higher carrier concentration, hole mobility and a longer lifetime of the carriers. Our work presents a new and simple phosphine-doping strategy for further improving the performance of CdTe NC solar cells.

An Interface Strategy on SnO2 for Stable Planar Perovskite Solar Cells

Defects and band shifts at the heterogeneous interface between the perovskite layer and the charge transport layer are two important problems that hinder the efficiency of photoelectric conversion and the stability of devices. Considering these issues, an interface engineering to reinforce the operation stability of FACsPbI3 perovskite solar cells (PSCs) by the introduction of a multifunctional ligand 2‐carboxyphenyl ethyl phosphate (CEPPA) modification layer between the electron transport layer and the perovskite layer is presented. It demonstrates that CEPPA adsorbs on the substrate surface to passivate the oxygen vacancy defects and effectively reduce the defect states on SnO2 films. On the other hand, the optimized arrangement of energy levels leads to better electron extraction and transport. Eventually, the power conversion efficiency (PCE) of the FACsPbI3 device increases from 16.33% to 17.78%. Moreover, compared with unmodified SnO2, the unpackaged devices with CEPPA‐modified SnO2 show better phase stability and moisture stability. Unpackaged devices retain more than 80% of their initial PCE after 500 h of aging. Herein, a further perspective for the analysis and development of buried interfaces and an effective approach for better improving the function and stability of PSCs are presented.

A Multifunctional Molecular Bridging Layer for High Efficiency, Hysteresis‐Free, and Stable Perovskite Solar Cells

AbstractAt present, the dominating electron transport material (ETL) and hole transport material (HTL) used in the state‐of‐the‐art perovskite solar cells (PSCs) are tin oxide and 2,2′,7,7′‐tetrakis(N,N‐di‐p‐methoxyphenyl‐amine)‐9,9′‐spirobifluorene (Spiro‐OMeTAD). However, the surface hydroxyl groups of the SnO2 layer and the Li+ ions within the Spiro‐OMeTAD HTL layer generally cause surface charge recombination and Li+ migration, significantly reducing the devices' performance and stability. Here, a molecule bridging layer of 3,5‐bis(fluorosulfonyl)benzoic acid (FBA) is introduced onto the SnO2 surface, which provides appropriate surface energy, reduces interfacial traps, forms a better energy level alignment, and, most importantly, anchors (immobilizes) Li+ ions in the ETL, and consequently improves the device power conversion efficiency (PCE) up to 24.26% without hysteresis. Moreover, the device with the FBA passivation layer shows excellent moisture and operational stability, maintaining over 80% of the initial PCE after 1000 h under both aging conditions. The current work provides a comprehensive understanding of the influence of the extrinsic Li+ ion migration within the cell on the device's performance and stability, which helps design and fabricate high‐performance and hysteresis‐free PSCs.

High-Performance Intrinsically Stretchable Polymer Solar Cell with Record Efficiency and Stretchability Enabled by Thymine-Functionalized Terpolymer.

Designing new polymer semiconductors for intrinsically stretchable polymer solar cells (IS-PSCs) with high power conversion efficiency (PCE) and durability is critical for wearable electronics applications. Nearly all high-performance PSCs are constructed using fully conjugated polymer donors (PD) and small-molecule acceptors (SMA). However, a successful molecular design of PDs for high-performance and mechanically durable IS-PSCs without sacrificing conjugation has not been realized. In this study, we design a novel thymine side chain terminated 6,7-difluoro-quinoxaline (Q-Thy) monomer and synthesize a series of fully conjugated PDs (PM7-Thy5, PM7-Thy10, PM7-Thy20) featuring Q-Thy. The Q-Thy units capable of inducing dimerizable hydrogen bonding enable strong intermolecular PD assembly and highly efficient and mechanically robust PSCs. The PM7-Thy10:SMA blend demonstrates a combination of high PCE (>17%) in rigid devices and excellent stretchability (crack-onset value >13.5%). More importantly, PM7-Thy10-based IS-PSCs show an unprecedented combination of PCE (13.7%) and ultrahigh mechanical durability (maintaining 80% of initial PCE after 43% strain), illustrating the promising potential for commercialization in wearable applications.

Improve Perovskite Solar Cell Stability and Efficiency via Multifunctional Multiple‐Ring Aromatic Dopant Passivation

Organic–inorganic perovskite solar cells, as a representative of the new generation of solar cells, have made satisfactory advancements in development over the past few years. However, the low carrier transport characteristics and energy loss brought on by defects severely restrict its development. This study develops a new liquid crystal material 1‐naphthalene acetic acid potassium salt (C12H9KO2, K‐NAA) as a dopant into the MA0.6FA0.4PbI3−xClx material. The presence of free K+ ions in K‐NAA modifies the perovskite lattice gap, and the CO structure can efficiently passivate the Pb2+ defect caused by the absence of coordination. Therefore, the grain boundaries, which serve as points of moisture penetration become blurred, hence suppressing charge trapping/recombination centers and enhancing the film quality and stability. The naphthalene in K‐NAA has a conjugated multiple‐ring aromatic structure. The abundant π‐electron delocalization present in the conjugated structure of the benzene ring may provide an electron‐rich environment outside the connected crystal structure, resulting in field‐effect passivation and effectively enhancing carrier transport performance. Hence, the devices deliver a champion power conversion efficiency (PCE) of 19.86%. After 700 h under the dark at 25 °C and 30% humidity, the optimized unencapsulated device PCE maintains at 92% of its initial efficiency.

Electron Acceptor Molecule Doping Induced π–π Interaction to Promote Charge Transport Kinetics for Efficient and Stable 2D/3D Perovskite Solar Cells

AbstractAlthough the incorporation of 2D perovskite into 3D perovskite can greatly enhance intrinsic stability, power conversion efficiency (PCE) of 2D/3D perovskite is still inferior to its 3D counterpart due to poor carrier transport kinetics resulted from the quantum and dielectric confinement of 2D component. To overcome this issue, the electron acceptor molecule 1,2,4,5‐tetracyanobenzene (TCNB) was introduced to trigger intermolecular π–π interaction in 2D perovskite along with the electronic doping of 2D/3D perovskite to improve charge transfer efficiency. By virtue of high electron affinity, TCNB can undergo electron transfer reaction and subsequently establish π–π interaction with 1‐naphthalenemethylammonium (NMA) cations, greatly strengthening lattice rigidity and reducing exciton binding energy. Transmission electron microscopy results demonstrate that 2D phases are mainly distributed at grain boundaries, reducing defect density and weakening nonradiative recombination. Meanwhile, the p‐type doping of perovskite by TCNB optimizes energy level alignment at perovskite/hole transport layer interface. Consequently, PCE of champion device is significantly boosted to 24.01 %. The unencapsulated device retains an initial efficiency close to 94 % after exposure to ambient environment for over 1000 h. This work paves a novel path for designing new mixed‐dimensional perovskite solar cells with high PCE and superior stability.

Electron Acceptor Molecule Doping Induced π-π Interaction to Promote Charge Transport Kinetics for Efficient and Stable 2D/3D Perovskite Solar Cells.

Although the incorporation of 2D perovskite into 3D perovskite can greatly enhance intrinsic stability, power conversion efficiency (PCE) of 2D/3D perovskite is still inferior to its 3D counterpart due to poor carrier transport kinetics resulted from the quantum and dielectric confinement of 2D component. To overcome this issue, the electron acceptor molecule 1,2,4,5-tetracyanobenzene (TCNB) was introduced to trigger intermolecular π-π interaction in 2D perovskite along with the electronic doping of 2D/3D perovskite to improve charge transfer efficiency. By virtue of high electron affinity, TCNB can undergo electron transfer reaction and subsequently establish π-π interaction with 1-naphthalenemethylammonium (NMA) cations, greatly strengthening lattice rigidity and reducing exciton binding energy. Transmission electron microscopy results demonstrate that 2D phases are mainly distributed at grain boundaries, reducing defect density and weakening nonradiative recombination. Meanwhile, the p-type doping of perovskite by TCNB optimizes energy level alignment at perovskite/hole transport layer interface. Consequently, PCE of champion device is significantly boosted to 24.01 %. The unencapsulated device retains an initial efficiency close to 94 % after exposure to ambient environment for over 1000 h. This work paves a novel path for designing new mixed-dimensional perovskite solar cells with high PCE and superior stability.

Semitransparent Solar Cells Employing n-Type Graphene on LaVO3.

To effectively utilize solar energy, semitransparent solar cells are essential in various fields such as building-integrated solar power generation and portable solar chargers. We report triethylenetetramine (TETA)-doped graphene (Gr) transparent conductive electrode (TCE)-based LaVO3 semitransparent solar cells. To optimize the Gr TCE, we varied the TETA molar concentration (nD) from 0.1 to 0.3 mM. TETA-doped Gr (TETA-Gr)/LaVO3 semitransparent solar cells exhibit the highest 1.45% efficiency and 62% average visible transmittance at nD = 0.2 mM. These results indicate that the TETA-Gr/LaVO3 structure not only harvests solar energy in the ultraviolet-visible region but also exhibits translucency, thanks to the thin film. Thanks to its translucent properties, we improved the power conversion efficiency (PCE) to 1.99% by adding an Al reflective mirror to the semitransparent cells. Finally, the device's PCE loss is only within 3% for 3000 h in air, suggesting good durability.

Influence of Halides on the Interactions of Ammonium Acids with Metal Halide Perovskites.

Additive engineering is a common strategy to improve the performance and stability of metal halide perovskite through the modulation of crystallization kinetics and passivation of surface defects. However, much of this work has lacked a systematic approach necessary to understand how the functionality and molecular structure of the additives influence perovskite performance and stability. This paper describes the inclusion of low concentrations of 5-aminovaleric acid (5-AVA) and its ammonium acid derivatives, 5-ammoniumvaleric acid iodide (5-AVAI) and 5-ammoniumvaleric acid chloride (5-AVACl), into the precursor inks for methylammonium lead triiodide (MAPbI3) perovskite and highlights the important role of halides in affecting the interactions of additives with perovskite and film properties. The film quality, as determined by X-ray diffraction (XRD) and photoluminescence (PL) spectrophotometry, is shown to improve with the inclusion of all additives, but an increase in annealing time from 5 to 30 min is necessary. We observe an increase in grain size and a decrease in film roughness with the incorporation of 5-AVAI and 5-AVACl with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Critically, X-ray photoelectron spectroscopy (XPS) measurements and density functional theory (DFT) calculations show that 5-AVAI and 5-AVACl preferentially interact with MAPbI3 surfaces via the ammonium functional group, while 5-AVA will interact with either amino or carboxylic acid functional groups. Charge localization analysis shows the surprising result that HCl dissociates from 5-AVACl in vacuum, resulting in the decomposition of the ammonium acid to 5-AVA. We show that device repeatability is improved with the inclusion of all additives and that 5-AVACl increases the power conversion efficiency of devices from 17.61 ± 1.07 to 18.07 ± 0.42%. Finally, we show stability improvements for unencapsulated devices exposed to 50% relative humidity, with devices incorporating 5-AVAI and 5-AVACl exhibiting the greatest improvements.

Quantum-sized TiO2 particles as highly stable super-hydrophilic and self-cleaning antisoiling coating for photovoltaic application

Soiling influences power generation and reduces the power conversion efficiency of solar energy conversion devices. In this regard, we successfully synthesized highly photocatalytic active quantum-size TiO2 particles with an average particle size of 6 nm and utilized the same to develop a highly transparent antisoiling coating. The material is characterized by small angle X-ray scattering, and the average particle size is found to be 6 nm. Automated spray coating technique was employed for the development of antisoiling coating on PV cover glass and minimodule. The coating exhibited exceptional weather stability (IEC 61646) for over 1500 h, excellent photoinduced superhydrophilicity in a span of 60 mins. Photocatalytic activity of the antisoiling coating is studied by analyzing the degradation of methylene blue and 4-chlorophenol. Promising antisoiling performance was observed from the antisoiling coated PV module as it resulted in 2.5% lower soiling loss compared to that of not-coated minimodules. The coatings exhibited excellent mechanical stability and Omni transparency.

Nanoscale Surface Analysis Reveals Origins of Enhanced Interface Passivation in RbF Post Deposition Treated CIGSe Solar Cells

AbstractAlkali post deposition treatments (PDTs) of Cu(In,Ga)Se2 absorbers have boosted the power conversion efficiency (PCE) of the solar cell devices in the last years. A detailed model explaining how the PDTs impact the optoelectronic properties at the nanoscale is still lacking. Here, via various scanning probe techniques, X‐Ray photo‐electron spectroscopy and high resolution secondary ion mass spectroscopy it is shown that the RbF PDT treatments lead to a one to one exchange of Rb with Cu at the surface. This exchange takes place in the naturally occurring Cu‐depleted CIGSe surface, known as the ordered vacancy compound. A detailed comparison between samples with different PDTs after various cleaning procedures furthermore highlights the necessity to perform all the measurements on NH4OH cleaning surfaces only. After NH4OH, no RbInSe2 phase could be detected at the surface anymore and the surface bandgap, as measured with scanning tunneling spectroscopy is only 1.7 eV. The findings demonstrate that the existence of a RbInSe2 phase is most likely not responsible for the recent improvements in power conversion efficiency for state of the art solar cells. The primary effect of the PDT treatment is a modification of the ordered vacancy compound, where Cu is exchanged with Rb.

Enhancing Photovoltaic Performance and Stability of Perovskite Solar Cells through Single-Source Evaporation and CsPbBr3 Quantum Dots Incorporation

This study investigates the potential of inorganic perovskite CsPbBr3 as a photovoltaic material, highlighting its superior stability compared to that of organic–inorganic hybrid perovskite materials. Conventional methods for preparing CsPbBr3 perovskite films, such as the two-step method and the dual-source thermal evaporation method, face challenges in obtaining high-purity films due to the decomposition of precursor films and the formation of multiple heterogeneous phases. To address this issue, we synthesized CsPbBr3 powder material using thermal evaporation deposition, which effectively suppressed decomposition and the formation of heterogeneous phases. Consequently, we achieved uniform and dense CsPbBr3 perovskite films. By incorporating energy-band engineering modification with CsPbBr3 quantum dots (QDs), the all-inorganic perovskite solar cells (PSCs) attained a power conversion efficiency (PCE) of 7.01% under standard solar illumination conditions. The device PCE remained at 93% of its initial efficiency under 30% relative humidity conditions for over 100 days, showcasing its durability. The developed method produced an average grain size of 800 nm, resulting in a smooth and uniform film surface, thereby demonstrating the method’s high repeatability. Additionally, the optimized PSCs exhibited a high open-circuit voltage (VOC) with the champion device reaching a VOC of 1.38 V and a PCE of 7.01%. This research presents a robust, efficient, and cost-effective approach for fabricating high-quality all-inorganic PSCs.