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Interface engineering is a simple and effective strategy for improving the photovoltaic performance and stability of perovskite solar cells (PSCs). Herein, an interface co-modification strategy is proposed, using [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and 2-fluoro-1,4-phenylenediammonium iodide (2FPPD) to modify the electron transport layer (ETL)/perovskite (PVK) and the PVK/hole transport layer (HTL) interfaces, respectively. A series of characterizations demonstrate that the PCBM&2FPPD interface co-modification strategy effectively enhances the extraction and transport efficiency of carriers at the interface, passivates surface defects, inhibits the nonradiative recombination of carriers, and simultaneously inhibits ion migration. Moreover, this strategy improves the crystallinity and surface hydrophobicity of PVK and optimizes the energy level alignment of PSCs. As a result, all photovoltaic parameters are improved after optimization, where the power conversion efficiency (PCE) of PSCs has increased from 17.01% to 18.36%. Meanwhile, the optimized PSCs show excellent environmental stability, which can be stably stored in air (RH = 10-20%) for about 800 h.

The eco-friendly and highly stable lead-free MAGeI_3 perovskite solar cell has proved itself as a potential candidate for conventional lead-based perovskite solar cells with high efficiency. In this paper, numerical simulation has been performed over MAGeI_3 solar cell with three different Electron Transport Layer (ETL) and Hole Transport Layer (HTL) materials to obtain the best combination of ETL/perovskite/HTL layers using the solar cell simulation tool SCAPS-1D. The best performance has been found for the ITO/ZnO/MAGeI_3/NiO_x structure with an efficiency of 21.19% (V_ of 1.89 V, J_ of 16.11 mA/cm^2, and FF of 69.57%) due to the higher bandgap and better carrier mobility of these two ETL and HTL materials. The thickness optimization indicated that a thickness below 1000 nm is suitable for better performance which also leads to a good indication of making a lightweight solar cell. This study indicates that the use of low-cost and environment-friendly ZnO and NiO_x with non-toxic MAGeI_3 perovskite has the potential to obtain a high-efficiency eco-friendly solar cell.

During the past few years, Tin (Sn)-based perovskites have been extensively investigated in the field of photovoltaics as promising candidates for new generation lead-free perovskite. Tin-based perovskites (ASnI3) present excellent photoelectric properties. However, there still remains a big concern over unsatisfactory stability. In reality, extensive efforts have been committed to improve the stability of perovskite active layer. In this review, a comprehensive understanding on defect formation, oxidation mechanism of Sn2+. Then, a detailed discussion on the recent advance the effect of additive engineering for the stability of FASnI3 PSCs, including antioxidants, 2D perovskite materials and functional passive molecular. Lastly, several key scientific issues and future research prospectives are proposed for achieving stable and high-performance Sn-based perovskite photovoltaics.

Chemically processed methylammonium tin-triiodide (CH3NH3SnI3) films include Sn in different oxidation states, leading to poor stability and low power conversion efficiency of the resulting solar cells (PSCs). The development of absorbers with Sn [2+] only has been identified as one of the critical steps to develop all Sn-based devices. Here, we report on coevaporation of CH3NH3I and SnI2 to obtain absorbers with Sn being only in the preferred oxidation state [+2] as confirmed by X-ray photoelectron spectroscopy. The Sn [4+]-free absorbers exhibit smooth highly crystalline surfaces and photoluminescence measurements corroborating their excellent optoelectronic properties. The films show very good stability under heat and light. Photoluminescence quantum yields up to 4 × 10^-3 translate in a quasi Fermi-level splittings exceeding 850 meV under one sun equivalent conditions showing high promise in developing lead-free, high efficiency, and stable PSCs.

Among alternative perovskite device architectures, mesoporous scaffolds based on metal oxide and carbon look highly promising due to their inherent high stability. In this study, the perovskite deposition has been realized on a 1.5 cm2 active surface area using inkjet infiltration through the mesoporous scaffold, affording a clean industrial process for large-scale and stable perovskite devices. A spectacular enhancement of photovoltaic performances from 10% to 14% was then obtained through the implementation of a maturation step. A study of the occurring mechanisms was conducted using a full set of characterization techniques including J-V measurements, UV–visible and PL spectroscopies, LBIC and PL imaging, XRD, and surface roughness measurements. In addition, the impact of this maturation step on the durability of the performances was investigated.

The development of stable materials, processable on alarge area,is a prerequisite for perovskite industrialization. Beyond the perovskiteabsorber itself, this should also guide the development of all otherlayers in the solar cell. In this regard, the use of NiO x as a hole transport material (HTM) offers severaladvantages, as it can be deposited with high throughput on large areasand on flat or textured surfaces via sputtering, a well-establishedindustrial method. However, NiO x may triggerthe degradation of perovskite solar cells (PSCs) when exposed to environmentalstressors. Already after 100 h of damp heat stressing, a strong fillfactor (FF) loss appears in conjunction with a characteristic S-shaped J-V curve. By performing a wide range of analysison cells and materials, completed by device simulation, the causeof the degradation is pinpointed and mitigation strategies are proposed.When NiO x is heated in an air-tight environment,its free charge carrier density drops, resulting in a band misalignmentat the NiO x /perovskite interface and inthe formation of a barrier impeding hole extraction. Adding an organiclayer between the NiO x and the perovskiteenables higher performances but not long-term thermal stability, forwhich reducing the NiO x thickness is necessary.

Di(9-methyl-3-carbazolyl)-(4-anisyl)amine is presented as an effective hole-transporting material suitable for application in perovskite solar cells. It is obtained by a three-step synthesis from inexpensive starting compounds. It has a relatively high glass transition temperature of 93 °C and thermal stability with 5% weight loss at 374 °C. The compound exhibits reversible double-wave electrochemical oxidation below +1.5 V and polymerization at higher potential. A mechanism for its oxidation is proposed based on electrochemical impedance and electron spin resonance spectroscopy investigations, ultraviolet-visible-near-infrared absorption spectroelectrochemistry results, and density functional theory-based calculations. Vacuum-deposited films of the compound are characterized by a low ionization potential of 5.02 ± 0.06 eV and hole mobility of 10-3 cm2/(Vs) at an electric field of 4 × 105 V/cm. The newly synthesized compound has been used to fabricate dopant-free hole-transporting layers in perovskite solar cells. A power conversion efficiency of 15.5% was achieved in a preliminary study.

Perovskite solar cells (PSCs) have shown a significant increment in power conversion efficiency recently with advantages such as flexibility and low-cost roll-to-roll production. Prior to the commercialization of PSCs, it is significant to investigate its environmental performance with life cycle assessment method. In this work, cradle to gate LCA of solution-based organo-lead iodide perovskite solar cell performed according to the one reported literature method that comprises flexible Polyethylene terephthalate (PET) substrate and hole transport layer (HTL) elimination. Environmental impacts from the generation of 1 m2 of cell area production are determined in six International Reference Life Cycle Data System (ILCD) categories. It is found that the major impact comes from the fabrication of the aluminum metal electrode layer due to the high electrical energy required in the vacuum deposition process. The life cycle global warming potential (GWP) that the most widely used environmental indicator has been calculated for per kWh electricity production to make a comparison with commercial photovoltaic technologies. It is found that the HTL-free flexible (HFF) PSC needs 15-20 years of device lifetime to reach competitive GWP value with commercial PVs.

Perovskite solar cell (PSC) has gradually shown its great superiority in photovoltaic filed to compete commercial solar cells owing to its great advantages, such as high efficiency and low fabrication cost. On the way towards commercialization, great efforts have been achieved by accelerating charge extraction and reducing carrier recombination. Recently, two-dimensional (2D) layered materials have attracted increasing interests for application in PSCs due to their distinctive chemical and physical properties, such as high carrier mobility and tunable bandgap, which greatly determines the perovskite film growth kinetics, carrier transfer and stability of PSCs. Therefore, with the aim to better understand their recent development and application in PSC, in this review, the emerging 2D materials beyond graphene as charge transport layers, buffer layers and additives in perovskite film for enhancing the efficiency and stability of PSCs are summarized. However, there are still some crucial challenges to be addressed for commercialization. Finally, the challenges and prospects of these 2D nanomaterials for application in PSCs are further proposed for future development.

All-inorganic perovskite solar cells (PSCs) have potential to pass the stability international standard of IEC61215:2016 but cannot deliver high performance and stability due to the poor interface contact. In this paper, Sn-doped TiO2 (Ti1−xSnxO2) ultrathin nanoparticles are prepared for electron transport layer (ETL) by solution process. The ultrathin Ti0.9Sn0.1O2 nanocrystals have greatly improved interface contact due to the facile film formation, good conductivity and high work function. The all-inorganic inverted NiOx/CsPbI2Br/Ti0.9Sn0.1O2 p-i-n device shows a power conversion efficiency (PCE) of 14.0%. We test the heat stability, light stability and light-heat stability. After stored in 85 °C for 65 days, the inverted PSCs still retains 98% of initial efficiency. Under continuous standard one-sun illumination for 600 h, there is no efficiency decay, and under continuous illumination at 85 °C for 200 h, the device still retains 85% of initial efficiency. The 1.0 cm2 device of inverted structure shows a PCE of up to 11.2%. The ultrathin Ti1−xSnxO2 is promising to improve the scalability and stability and thus increase the commercial prospect.

Although perovskite solar cells have achieved excellent photoelectric conversion efficiencies, there are still some shortcomings, such as defects inside and at the interface as well as energy level dislocation, which may lead to non-radiative recombination and reduce stability. Therefore, in this study, a double electron transport layer (ETL) structure of FTO/TiO2/ZnO/(FAPbI3)0.85(MAPbBr3)0.15/Spiro-OMeTAD is investigated and compared with single ETL structures of FTO/TiO2/(FAPbI3)0.85(MAPbBr3)0.15/Spiro-OMeTAD and FTO/ZnO/(FAPbI3)0.85(MAPbBr3)0.15/Spiro-OMeTAD using the SCAPS-1D simulation software, with special attention paid to the defect density in the perovskite active layer, defect density at the interface between the ETL and the perovskite active layer, and temperature. Simulation results reveal that the proposed double ETL structure could effectively reduce the energy level dislocation and inhibit the non-radiative recombination. The increases in the defect density in the perovskite active layer, the defect density at the interface between the ETL and the perovskite active layer, and the temperature all facilitate carrier recombination. Compared with the single ETL structure, the double ETL structure has a higher tolerance for defect density and temperature. The simulation outcomes also confirm the possibility of preparing a stable perovskite solar cell.

Department of Applied Sciences Undergraduate Student, , Haldia Institute of Technology ,West Bengal, India Department of Physics, Balurghat College, West Bengal, India Corresponding Author’s Email: rajeshhitsas2022@gmail.com ZnO nanostructures play important role as potential material due to their wide bandgap, high electron mobility, excellent electronic and photonic properties. Various ZnO nanostructures are very much useful to improve electron extraction efficiency to replace TiO2 as electron transport layer (ETL) in organic-Inorganic metal halide perovskite (CH3NH3PbX3) based hybrid solar cell. Thin film perovskite solar cell draws technical interestfor its high efficiency (25.2%, highest laboratory record) and low cost. Various forms of TiO2 nanostructure plays important role due to its high extinction coefficient, high charge mobility, long carrier lifetime, and long carrier diffusion length. TiO2 nanostructure plays dual role as a light absorbing material as well as an electron/hole transport layer in perovskite solar cell. Doped and undopedZnO, undoped TiO2 powder are synthesized by sol-gel route followed by rapid thermal annealing. Solution-processed ZnO and TiO2 nanostructure at low temperatures yields different morphologies, and variation of band-gap with grain size. Structural and optical characterizations are carried out by XRD, SEM and UV-VIS spectroscopy respectively.ZnO is hexagonal-wurtzite polycrystalline II-VI compound semiconducting structure with (002) preferred orientation. Heat treated ZnO powder sample shows the miller indices of (100),(002), (102), and (004). Room temp TiO2 powder samples show its amorphous phase but rutile and anatase phases are present after heat treatment.

The most widely used material as a hole-transport layer (HTL) for effective normal perovskite solar cells (PSCs) is still 2,2′,7,7′-Tetrakis[N, N-di(4-methoxyphenyl)amino]-9,9′-spirobifluorene (Spiro-OMeTAD), which requires heavy doping with the hydroscopic Lithium bis(trifluoromethanesulfonyl)imide (Li-ΤFSI). However, the long-term stability and performance of PCSs are frequently hampered by the residual insoluble dopants in the HTL, Li+ diffusion throughout the device, dopant by-products, and the hygroscopic nature of Li-TFSI. Due to the high cost of Spiro-OMeTAD, alternative efficient low-cost HTLs, such as octakis(4-methoxyphenyl)spiro[fluorene-9,9′-xanthene]-2,2′,7,7′-tetraamine) (X60), have attracted attention. However, they require doping with Li-TFSI, and the devices develop the same Li-TFSI-derived problems. Here, we propose Li-free 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMIM-TFSI) as an efficient p-type dopant of X60, resulting in a high-quality HTL with enhanced conductivity and deeper energy levels The optimized X60:EMIM-TFSI-enabled devices exhibit a higher efficiency of 21.85% and improved stability, compared to the Li-TFSI-doped X60 devices. The stability of the optimized EMIM-TFSI-doped PSCs is greatly improved, and after 1200 hr of storage under ambient conditions, the resulting PSCs maintain 85% of the initial PCE. These findings offer a fresh method for doping the cost effective X60 as the HTL with a Li-free alternative dopant for efficient, cheaper, and reliable planar PSCs.

The technology of organometal halide perovskites is on the verge of the lab to fab transition due to particularly high efficiencies and low cost of the raw materials employed in the active later. The hole transport layer is a key enabling component of such solar cells and at the same time the one requiring more significant synthetic efforts. Alternative materials with improved sustainability are under constant development, yet 2,2′,7,7′-tetrakis(N,N-di(4-methoxyphenyl)amino)-9,9′-spirobifluorene (Spiro-OMeTAD) still represents the standard in the field. We show that the combination of solventless approaches, chemistry on water, and micellar catalysis gives access to such critical material in a fully sustainable, scalable, and efficient way. Performances are validated in devices delivering results equal to those with standard commercial Spiro-OMeTAD but greatly reducing the overall E-factor─a green chemistry metric measuring the waste/purified product ratio of a synthesis, from 5299 to 555, as well as eliminating chlorinated solvents and hazardous chemicals.

Majority of spacecrafts rely on solar power as the main source of energy. The search for a lightweight and cost-efficient energy source with high power conversion efficiency (PCE) led to the development of organic-inorganic metal halide Perovskite solar cells (PSCs). In this paper, the performance of PSCs with different hole-transport material (HTM) prepared for in-orbit demonstration mission onboard CubeSats are compared under simulated space environment such as thermal cycling stress, high-vacuum, UV radiation and vibration. Results show that even though organic and inorganic HTM display superior initial PCE, Carbon HTM PSCs trumps them in terms of stability and is more practical for use in space. The paper also discusses the satellite mission and developed hardware for the first demonstration of Perovskite solar cells on-board a satellite to gather in-orbit information on the performance of Perovskite solar cells in low-earth orbit and how the ground test results would be verified.

Perovskite solar cells (PSCs) have become a promising photovoltaic (PV) technology. Meanwhile, developing an electron transport layer (ETL) has been an effective way to promote the power conversion efficiency (PCE) of PSCs. Here, a 4-morpholine ethane sulfonic acid sodium salt (MES Na+) doped SnO2 ETL is utilized in planar heterojunction PSCs. The results show that the MES Na+ doped ETL can improve the crystallinity, and absorbance of perovskite films, and passivate interface defects between the perovskite film and SnO2 ETL. The doping effect accounts for the enhancement of conductivity and the decreasing work function of SnO2. When 10 mg mL-1 MES Na+ was added to the SnO2 precursor solution, the device showed the best performance Jsc, Voc, and FF of the PSCs values, which were 23.88 mA cm-2, 1.12 V and 78.69%, respectively, and the PCE was increased from 17.43% to 21.05%. This doping ETL strategy provides an avenue for defect passivation to further increase the efficiency of perovskite solar cells.

Before completely applying inorganic materials as hole transport materials (HTM) for perovskite solar cells (PSCs), modifying devices with inorganic oxides that have the potential as inorganic hole transporters is an effective way to improve device performance and stability. Co2+ doped CuGaO2 nanocrystals (Co-CuGaO2 NCs) with sizes about 20 nm are synthesized by hydrothermal method and used for surface passivation at the interface of perovskite (PVK)/2,2′,7,7′-Tetrakis[N,N-di (4-methoxyphenyl) amino]-9,9′-spirobifluorene (spiroOMeTAD). Co-CuGaO2 NCs have a larger bandgap with lower valance band compared with spiroOMeTAD, which is more beneficial to the conduction of holes and the blocking of electrons. Furthermore, the Co-CuGaO2 has a lower valance band energy compared with the original CuGaO2, which reduces the energy gap between Co-CuGaO2 and PVK. Co-CuGaO2 NCs fully cover the upper surface of PVK, which helps prevent direct contact between PVK and oxygen and moisture. The Co-CuGaO2 NCs surface passivation also gives better hole transport as revealed by the ultraviolet photoelectron spectroscopy (UPS), steady-state photoluminescence (PL), and time-resolved photoluminescence (TRPL) data. When the concentration of Co-CuGaO2 NCs solution is set to 7.5 mg mL−1, the device exhibits a best PCE of 20.39% and maintains 84.34% of the initial power conversion efficiency (PCE) after stored 30 days under air atmosphere with 15 ± 5% humidity.

The replacement of small cations with bulkier organic cations containing long alkyl chains or benzene rings to form a thin two-dimensional (2D) perovskite passivation layer on three-dimensional (3D) perovskite (2D/3D) has become a promising strategy for improving both the efficiency and stability of perovskite solar cells (PSCs). The 2D layer defines the interfacial chemistry and physics at the 2D/3D bilayer and endows the 2D/3D structure with better chemical and thermal stability. Herein, 2D/3D (CF3-PEA)2FA0.85MA0.15Pb2I7/FA0.85MA0.15PbI3 planar heterojunction perovskite was produced using a facile interfacial ion exchange process. The 2D (CF3-PEA)2FA0.85MA0.15Pb2I7 capping layer can not only passivate the FA0.85MA0.15PbI3 film but also act as super-hydrophobic layer to inhibit water diffusion and significantly enhance the stability. The 2D capping layer can also establish a unique graded band structure at the perovskite/Spiro-OMeTAD interface and lead to p-type doping for Spiro-OMeTAD layer which is beneficial for efficient charge transport. Optimized PSCs based on this 2D/3D heterojunction yield a champion power conversion efficiency (PCE) of 23.1% and improved stability. The device maintains 84% output for 2400 h aging under ambient environmental conditions without encapsulation, and maintains 81% for 200 h under illumination with encapsulation. This work will inspire the design of more fluorinated 2D perovskite interfaces for advanced photovoltaics and beyond.

Solar energy is the centre of attention and major need of the world. The advancement in the photovoltaic devices plays the key role in the path of solar energy applications. The progress in the perovskite solar cell technologies in the direction of their theoretical power conversion efficiency necessitates elusive control above the carrier dynamics all over the whole device. In the present investigation, a comparative study via SCAPS simulation has been done for the optimization of the device in the light of high power conversion efficiency of organic–inorganic perovskite-based photovoltaic solar cells. Perovskite absorber layers CH3NH3PbI3 and CH3NH3SnI3 are sandwiched in between the TiO2 as electron transport layer (ETL) and spiro-OMeTAD as hole transport layer (HTL) to design the hetrostructures for the simulation. We have achieved enhancement in the power conversion efficiencies of both the devices as compared to the reported experimental and theoretical studies previously.

The optimization of thickness and surface roughness of the TiO2 layer as an efficient electron transporting layer (ETL) plays a significant role on the performance improvement of perovskite solar cells (PSCs). In the present investigation, TiO2 pastes synthesized with various concentrations under hydrothermal conditions were utilized to deposit the TiO2 films of tunable porosities as the ETLs of PSCs. Also, the PSCs were fabricated with a structure of FTO/block-TiO2 (b-TiO2)/m-TiO2/CH3NH3PbI3 (MAPbI3)/CuInS2 (CIS)/carbon as a low-cost architecture. Moreover, the effect of the TiO2 paste concentration was studied on the performances of PSCs under fully ambient conditions. The optimal TiO2 layer was constructed with 20 wt% TiO2 paste concentration, which resulted in the formation of a hole‐free, smooth, and compact ETL layer. The champion perovskite solar cell fabricated with the 20 wt% TiO2 paste concentration showed the highest power conversion efficiency (PCE) of 13.09% (JSC = 20.80 mA cm−2, VOC = 0.98 V and FF = 0.64) but the champion PSC device made with the 10 wt% TiO2 paste exhibited the lowest PCE = 8.05% (JSC = 19.83 mA cm−2, VOC = 0.91 V and FF = 0.45). These results illustrated that the optimal 20 wt% TiO2 paste caused ∼163% enhancement in the PCE of the device. Consequently, it could be suggested for application in fabrication of cost-effective and large scale PSCs.

The development of quasi-two-dimensional (2D) Ruddlesden-Popper phase perovskite solar cells (PSCs) has greatly improved the stability of devices. However, the presence of quantum confinement effects and insulating spacer cations in 2D perovskite films will widen the bandgap and hinder carrier transportation, thereby discounting the efficiency of 2D PSCs. Here, a quantum well reversely graded structure is introduced into FA-MA mixed 2D perovskite films via isopropanol washing. 2D perovskites, mainly the n=2 phase, are concentrated at the top of the film. We find that half of the spacer cations are washed away by isopropanol, and the average n-value evolves from 5 in the precursor to about 18 in the final annealed film. As a result, the quantum confinement effect inside the film is weakened, and the external quantum efficiency response wavelength is extended to 812 nm. More importantly, the film shows out-of-plane orientation, enlarged apparent grain size (688 nm), and a long carrier lifetime (936 ns). A record-high power conversion efficiency (PCE) of 20.12% is achieved. The unencapsulated device retains 98% of its initial PCE after aging at 30±5% relative humidity for 2000 h, and 96% after continuous working at maximum power point for 360 h. The fine regulation of quantum wells can be the answer to highly efficient and highly stable PSCs.

Lead free and environment friendly, light absorbing material is in high demand for the photovoltaic perovskite solar cell devices. The double perovskite La2NiMnO6 have the centre of attention for this demand. The present review is focused to discuss briefly the progress and challenges in the structural and magnetic properties of La2NiMnO6 in bulk, nano and thin film phases. The structural changes of La2NiMnO6 are highly interesting and have the direct correlation with the magnetic properties. On the basis of these transformations in the structure, efforts have been made to discuss several scientific progresses into technical novelties. This short review article is critically dedicated on reviewing the progresses, openings, and upcoming challenges in perovskite solar cell devices.

Nowadays solar cell is one of the best techniques for energy harvesting, we are using CH3NH3PbI3 perovskite material for solar cells applications. One of the most exciting developments in photovoltaics over recent years has been the emergence of perovskite (CH3NH3PbI3) as a promising new material for low-cost, high-efficiency photovoltaics. In this paper, we are assuming the layer of perovskite free from defects. A solar cell simulation software GPVDM, which works as a popular solar cell simulation tool (AMPS: Analysis of microelectronic and photonic structures) was used. The simulation model solves drift–diffusion of electron and hole, carrier continuity equations in position space to describe the movement of charge within the device, poison’s equation, and recombination of charge carriers.

Both nanosecond pulses and picosecond laser pulses are used for P2 patterning of chalcopyrite (Cu(In,Ga)Se2, CIGSe) and metal halide perovskite solar cell absorber layers. For CIGSe, the range of the modified material visualized by photoluminescence imaging is significantly wider than the actual physical linewidth, since energy input by the laser pulses leads to material modification in the vicinity of the scribed lines. This effect does not occur with the perovskite absorber layers, where there is no apparent influence on the edge regions. From numerical calculations of the temperature depth-profiles and the surface temperature distributions it is concluded that this effect is due to the significantly lower perovskite absorber layer thickness compared to CIGSe and the nevertheless significantly higher laser fluence required for perovskite ablation. The unaffected edge regions around the P2 line in the perovskite enabled a reduction of the dead area width in the fabrication of 3-segmented mini-modules, which could be significantly reduced from 430 to 230 µm, while increasing the aperture area power conversion efficiency and also the geometric fill factor, which could be increased up to 94.6%.

Self-assembly of reduced graphene oxide, zinc [5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin] complex and CuO nanoparticles was performed through π–π stacking and hydrogen bonding using Calotropis procera plant to have a bio-nanocomposite (ZnPor/rGO/CuO). This green organic/inorganic ternary hybrid was constructed using bottom-up approach to have multiple electron transfer and characterized by SEM, TEM, XRD, EDX, elemental analysis, UV–Vis spectroscopy, and Cyclic voltammetry (CV). The bio-nanocomposite (ZnPor/rGO/CuO) possesses suitable energy level, high hole mobility, and excellent thermal stability. The obtained bio-nanocomposite was used as inorganic hole-transporting material (HTM) in carbon-based Perovskite Solar Cells (C-PSC). 9.8 is the best powder conversion efficiency of system in comparision with Spiro-OMeTAD as a commercial HTM. Its PCE is about 59% more than of PCE of control device (HTM free). This significant increase in PCE was due to the higher hole-extraction rate at carbon counter-electrode, in the presence of bio nanocomposite as a HTM confirming by Mott–Schottky analysis and the electrical conductivity.

In the conventional sandwich structure of perovskite solar cells (PSCs) with the metallic electrodes, the parasitic absorption losses due to the presence of glass substrate, conductive metal oxides and other functional layers below the perovskite film reduce a certain portion of photons that can be harvested by the perovskite absorber. The carbon quantum dots (CQDs) with down-converting properties can absorb high-energy UV light and convert them into the photons with lower energy lying in the visible light region. The CQDs can be used to enhance the light harvesting power of the PSCs so that the negative effect due to the parasitic absorption can be suppressed. In this work, a coating layer composed of CQDs is deposited on the illuminated side of the glass substrate. In contrast to our previous report, the deionized water (DIW) is used to disperse the CQDs instead of dispersing CQDs in the matrix of PMMA and chlorobenzene (CB). By using the new approach, the preparation of CQD coatings is more efficient and the use of toxic CB can be avoided. After systematic optimization of the preparation parameters, it is found that using water as the dispersion medium for CQDs can also yield the effective coatings for PSCs to enhance their light absorption power.

The impact of hysteresis on the power conversion efficiency (PCE) of perovskite solar cells (PSCs) still faces uncertainties despite the rapid development of perovskite photovoltaics. Although ion migration in perovskites is regarded as the chief culprit for hysteresis, charge carrier recombination pathways in PSCs are proposed to be necessary for the occurrence of hysteresis. Here, the impact of both bulk recombination and interface recombination on hysteresis in PSCs is investigated via drift–diffusion modeling. The simulation results demonstrate a direct correlation between recombination pathways and hysteresis in PSCs with ion migration. The simulation reveals that recombination pathways in PSCs will react to the variation in charge carrier distribution under different voltage scanning directions induced by ion migration in absorber layers, which leads to hysteresis in PSCs. Moreover, the hysteresis in normal (N-I-P) PSCs with different electron transport layers (ETLs) including sintered SnO2, SnO2 nano crystals and TiO2 is experimentally explored. The results demonstrate that multiple recombination pathways coupled with ion migration can lead to obvious hysteresis in fabricated PSCs which is consistent with simulation results. This work provides great insight into hysteresis management upon composition, additive and interface engineering in PSCs.

Effectively encapsulating perovskite solar cells (PSCs) to enhance the external reliability is the key towards commercialization. We herein propose a facile encapsulation method by introducing conductive ribbons and a polyethylene terephthalate (PET) backsheet on both sides of PSC. Via applying thermoplastic polyolefin (TPO) encapsulant, we implemented PSCs with fine encapsulation, enabling considerable durability in the ambient atmosphere and even with water immersion, demonstrating almost no degradation in the device output, which is ascribed to the low water vapor transmission rate as well as the high chemical stability of TPO. The operation reliability of the encapsulated cell is also significantly increased, maintaining 80% of the initial efficiency after 770 hours’ light illumination in an ambient atmosphere. This novel encapsulation route provides a feasible idea for the commercial application of PSCs in the future.

Perowskite sind eines der vielversprechendsten Materialien f ¨ ur die n¨achste Generation von Solarzellen, insbesondere die Kombination einer Perowskit Topsolarzelle mit einer Silizium Bottomsolarzelle in einer Tandemsolarzelle. Perowskitsolarzellen werden jedoch durch verschiedene Umwelteinfl¨ usse beeintr¨achtigt, und sowohl die Langzeitstabilit¨at als auch die Reproduzierbarkeit des Herstellungsprozesses sind nach wie vor wichtige Probleme, die noch nicht gel¨ost sind. In dieser Arbeit werde ich die Herstellung von Perowskitsolarzellen mit dem aufgedampften Perowskit MAPbI3 detailliert beschreiben. Ich werde zeigen, dass diese Solarzellen derzeit vor allem unter zwei Mechanismen leiden, die denWirkungsgrad begrenzen und eine Degradation verursachen. Der erste ist die Degradation durch Feuchtigkeit, die haupts¨achlich durch hygroskopisches MAI in der Perowskitschicht verursacht wird, da unsere Prozessierung und Messung teilweise in Umgebungsatmosph¨are stattfindet. Der zweite Effekt wird durch Ionenbewegung im Perowskit verursacht, die Hystereseeffekte und, sobald die Metallelektrode der Perowskitsolarzelle abgeschieden ist, auch langfristige Degradation verursacht. Ich werde skizzieren, wie beide Effekte in Zukunft durch Optimierungen der Herstellungs- und Messbedingungen bestimmt und minimiert werden k¨onnen. Erste Experimente mit einigen dieser Optimierungen zeigen bereits Zellwirkungsgrade von bis zu 17%. Im zweiten Teil dieser Arbeit werde ich optische Simulationen sowohl von Perowskit-Single-Junction Solarzellen als auch von Perowskit-Silizium-Tandemsolarzellen vorstellen. F¨ ur die Perowskit- Single-Junction Solarzellen mit aufgedampftem MAPbI3 werde ich ein effektives Medium-Modell vorstellen, das verwendet werden kann, um variierende Absorption in PbI2 reichen MAPbI3 zu beschreiben. F¨ ur die Tandemsolarzellen werde ich die Auswirkungen der Vorder- und R¨ uckseitentextur sowie einen neuartigen Poly-Silizium-Rekombinations ¨ ubergang zwischen den Perowskit- und Silizium- Subzellen auf die Stromerzeugung untersuchen., Perovskites are one of the most promising materials for next generation photovoltaics, especially the combination of a perovskite top solar cell with a silicon bottom solar cell in a tandem solar cell. Perovskite solar cells however suffer from degradation due to several ambient effects and long term stability as well as process reproducibility are still major issues to overcome. In this thesis I will explain the processing of perovskite solar cells with the evaporated perovskite MAPbI3. I will show that these devices currently suffer mostly from two effects that limit efficiency and cause degradation. The first is degradation due to moisture mainly caused by hygroscopic MAI in the perovskite layer, since our processing and measurement partially takes place in ambient atmosphere.The second effect is caused by ionic movement in the perovskite, which causes hysteresis effects as well as long term degradation once the metal electrode of the perovskite solar cell is deposited. I will outline how to measure and minimize both effects in future with optimisations in the processing and measurement conditions. First experiments including some of these optimisations already show cell efficiencies up to 17%. In the second part of this work I will present optical simulations of both single-junction perovskite and perovskite-silicon tandem solar cells. For the perovskite single-junction cells with evaporated MAPbI3 I will present an effective medium model that can be used to identify the varying absorption in the PbI2 rich MAPbI3. For the tandem solar cells I will discuss the optical effects of front and rear side texture as well as a novel poly-silicon recombination junction in between the perovskite and silicon subcells.

Perovskite solar cells are the most dynamic emerging photovoltaic technology and attracts the attention of thousands of researchers worldwide. Recently, many of them are targeting device stability issues–the key challenge for this technology–which has resulted in the accumulation of a significant amount of data. The best example is the “Perovskite Database Project,” which also includes stability-related metrics. From this database, we use data on 1,800 perovskite solar cells where device stability is reported and use Random Forest to identify and study the most important factors for cell stability. By applying the concept of learning curves, we find that the potential for improving the models’ performance by adding more data of the same quality is limited. However, a significant improvement can be made by increasing data quality by reporting more complete information on the performed experiments. Furthermore, we study an in-house database with data on more than 1,000 solar cells, where the entire aging curve for each cell is available as opposed to stability metrics based on a single number. We show that the interpretation of aging experiments can strongly depend on the chosen stability metric, unnaturally favoring some cells over others. Therefore, choosing universal stability metrics is a critical question for future databases targeting this promising technology.

In this paper, a modified bald eagle search optimization algorithm was applied for the first time to determine the parameters of the triple diode model (TDM) of perovskite solar cells (PSCs). Two experimental datasets are considered; the first is measured I–V points for a PSC at standard conditions. The second consists of the measured I–V points for a modified PSC. In contrast, the cost function to be minimized is the root mean square error (RMSE) between the experimental dataset and the calculated one. To prove the superiority of modified bald eagle search optimization (mBES), a comparison with the original bald eagle search optimization (BES), particle swarm optimizer (PSO), Hunger games search (HGS), and recent Coronavirus Disease Optimization Algorithm (COVIDOA) was implemented. Furthermore, statistical analysis of ANOVA and Tukey tests was performed. The results demonstrate the lead of the recommended mBES in identifying the parameters of the TDM for PSCs, where the RMSE achieved the least value among the used optimization algorithms in this study.

Solar cells have been powering satellites since the beginning of space exploration. As “commercial” space activities are increasing driven by decreasing launch and manufacturing costs, new space solar cell technologies that are of low cost will be needed. Organometal halide perovskite solar cells (PSCs) are promising for this due to their high efficiencies, low manufacturing cost, and radiation hardness warranting research and development. For this, the first experimental work of this thesis reports passivation strategies for perovskites fabricated by gas-quenching to reduce the use of toxic solvent for high efficiency cell demonstration. The strategies involve the incorporation of potassium iodide (KI)) in the perovskite and the deposition of n-hexylammonium bromide (HABr) onto the perovskite surface producing an efficiency of 23.6% for champion device. For better stability critical for operations in space, the progress and opportunities of Cs incorporated perovskites were reviewed, thereby inspiring the demonstration of CsFA perovskite cells optimised on sub-millimetre thin (175-μm) sapphire substrate as part of the second experimental work. High power-to-weight ratios over 200 mW/g were demonstrated - highest amongst PSCs used for proton irradiation studies. The last experimental work compares radiation hardness of 3 different types of hole transport materials (HTMs) for PSCs. HTM with tris(pentafluorophenyl)borane (TPFB) as a dopant was found to be more radiation tolerant than that with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) dopant. The more superior cells also recovered from radiation damage via thermal vacuum that can be facilitated by solar irradiation on low earth orbit. Thermal admittance spectroscopy (TAS) and deep-level transient spectroscopy (DLTS) were used to characterize radiation-induced defects in PSCs for the first time at the time of reporting. The thesis concludes with an outlook for future work based on findings from this thesis.

A series of organic electron-rich π-bridged symmetric hydrazones, composed of two donor moieties connected through a thiophene- or a pyrrole-based π-spacer, has been synthesized as a suitable alternative to 2,2’,7,7’-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9’-spirobifluorene (Spiro-OMeTAD), considered the benchmark hole transporting material (HTM) in perovskite solar cells (PSCs). The cheap synthetic protocol is suitable for potential large-scale production. All the compounds were characterized, showing good energy levels alignments with the perovskite and very close energy levels to the Spiro-OMeTAD. Furthermore, computational analysis confirmed the electrochemical trend observed. The costs of synthesis were estimated, as well as the produced waste to synthesise the final HTMs, underlining the low impact of these compounds on the environment with the respect to Spiro-OMeTAD. Overall, the relevant electrochemical properties and the low cost of the synthetic approaches allow these compounds to be a greener and easy-to-synthesize alternative to the Spiro-OMeTAD for industrial development of PSCs.

Perovskite solar cells (PSC) are under focus in the field of renewable energies due to the exceptional photoconversion efficiencies achieved in a short period of time. Even though the laboratory reports are very promising, it is necessary to perform a scale-up feasibility analysis to determine if PSCs can become a widely used technology. In this report we evaluated the energy performance with energy indicators from Net Energy Analysis (NEA). We performed a cradle-to-gate life cycle assessment (LCA) of a n-i-p PSCs fabricated in the Buenos Aires city area to focus on the energy supply from the life cycle inventory. The energy payback time (EPBT) and the energy return of investment (EROI) were analyzed in order to examine the energy generation and the lifetime requirements of the perovskite photovoltaic modules to provide a resourceful commercialization pathway. The EPBT was analyzed under different solar irradiation values for varied locations throughout the vast Argentinian territory, that ranges between 0.97 and 1.74 years for 15% efficiency modules. A further evaluation of the addition of an extra encapsulation step for stability purposes was also studied. We also analyzed the inverted configuration of MAPbI3 solar cells in order to compare both production process and their effect on the energy performance. We were able to state that the different processing energy provides better outcomes for the p-i-n configuration and must be prioritized for commercialization purposes.

In recent years, have been seen a leap at the opportunity of investigation tandem solar cells. This due to the complementary bandgap energies of various layers which leads to enhancement of the light absorption and the power conversion efficiency (PCE) of this type of solar cells. In this numerical based study, a new hole transport material (HTM) free perovskite/quantum dot solar cell, exploiting a finite element method (FEM), has been conducted for the first time. The series connection of perovskite (CH3NH3PbI3, 1.55 eV) and colloidal quantum dot (CQD) of lead sulphide (PbS-CQD, 1.3 eV) as light-carrier absorber layers is analysed to achieve the optimal performance with short-circuit current (Jsc) = 25.4 mA/cm2, open-circuit voltage (Voc) = 0.8 V, fill factor (FF) = 0.84. The simulation results illustrate that tandem solar cell yields an overall PCE of 17.2%, exceeding that of 14.53 % of bare perovskite absorbing layer in planar perovskite solar cell (PSC). To enhance the light absorption within the absorber layer and consequently to achieve a higher efficiency, pyramidal texturing of layers, as an effective light-management method was investigated and it reveals that the Jsc and PCE is increased to 29.3 mA/cm2 and 19.52% respectively. Comparing to the planar perovskite architecture, PCE is improved from 14.53% to 19.52%, indicating a great potential of nanostructure designing in tandem solar cells.

In this article, we have developed an ex-ante life cycle assessment (LCA) for the FTO/TiO2/Cs2TiX6/CuSCN/Ag Where, X = Br-, I-, Cl-, Fand FTO/TiO2/Cs2TiI6-XBrX (where x = 1 to 5)/CuSCN/Ag structure based Perovskite solar cell PV model to determine the total primary energy demand by each layer (TPED), annual primary energy generation of the system (APEG), energy payback time (EPBT) and energy returned on energy invested (EROI) of the module. In our study, we have found that the total primary energy demand for all the PV module is 110.46 MJ/m2 and annual primary energy generation for the Cs2TiBr6, Cs2TiI6, Cs2TiCl6, Cs2TiF6, Cs2TiI1Br5, Cs2TiI2Br4, Cs2TiI3Br3, Cs2TiI4Br2, and Cs2TiI5Br1 Perovskite material based PV module is 225.04 MJ, 254.9 MJ, 85.95 MJ, 189.7 MJ, 282.4 MJ, 351.32 MJ, 335.07 MJ, 317.87 MJ and 267.71 MJ respectively. The EPBT (Year) for the Cs2TiBr6, Cs2TiI6, Cs2TiCl6, Cs2TiF6, Cs2TiI1Br5, Cs2TiI2Br4, Cs2TiI3Br3, Cs2TiI4Br2, and Cs2TiI5Br1 Perovskite material based PV module is 0.49, 0.43, 1.29, 0.58, 0.39, 0.31, 0.33, 0.35 and 0.41 respectively and their corresponding EROI is 30.61, 34.88, 11.63, 25.86, 38.46, 48.39, 45.45, 42.86 and 36.59 respectively. The various environmental profiles was discussed with 14 most significant impact for the PV module.

So far, halide perovskite solar cells (PSCs) have been known as the important devices having significant growing efficiency, despite of their not so impressive stability compared to other types of solar devices. Among the stability research, thermal stability of halide PSCs is still a challenge for their commercialization. Therefore, in this study, the degradation mechanism on thermal instability has been explored using different ways including morphological analyses and transient photocurrent measurements, the transient photoconductivity, dielectric and noise measurements and low-frequency noise measurement. The strategies suppressing the thermal instability have been explained basing on the aspects of the electron transport layers (ETLs) like doping of the ETL and employing double layers; light absorption layers such as grain passivation; hole transport layers (HTLs) which may include use of dopant free HTL and graded hybrid structure of layers as well as the 2D perovskites. Therefore, this review is expected to contribute towards development of perovskite solar cell materials and promote practical applications.

Hybrid perovskite solar cell (PSC) has attracted extensive research interest due to its rapid increase in efficiency, regarding as one of the most promising candidates for the next-generation photovoltaic technology. The certified power conversion efficiency of the devices based on formamidinium lead iodide (FAPbI3) perovskite has reached 25.5%, approaching the record of monocrystalline silicon solar cells. Unfortunately, the black α-phase FAPbI3 materials can spontaneously transform to non-optically active δ-phase at room temperature, which greatly hinder their photovoltaic application. In order to overcome this problem, various strategies, especially introducing methylammonium (MA+), caesium (Cs+) and bromide (Br-) ions into the materials, have been widely adopted. However, MA+ can largely reduce the thermal stability of the materials. Furthermore, the introduction of Br- can enlarge the materials’ bandgap, resulting in a reduced theoretical efficiency. Keeping these in mind, developing the strategies which without using MA+ and Br- is the inevitable trend. Here, we focus on the recent progresses of stabilizing α FAPbI3 without employing MA+ and Br-, and discuss the advantages of inorganic ions doping and dimensionality engineering to stabilized α FAPbI3. Meanwhile, in order to deeply understand the relationship between the semiconducting properties and device performance of the corresponding materials, we then summarize several significant strategies to suppress the non-radiation recombination, such as interface modification and trap passivation. Finally, we propose to develop more effective ‘A-site’ alternatives to stabilize α FAPbI3, which is expected to achieve high-efficient PSCs with long-term stability, facilitating its commercialization process.

At present, there are many reports on the preparation of large area perovskite solar cells based on ink-jet printing. These works mainly focus on the ink-jet printing electrode and perovskite films. The hole transport layer, electron transport layer and other modified layers in the cell structure are still completed by spin coating or coating. We have successfully realized large area CH3NH3PbI3 perovskite solar cells based on all inkjet printing, including PEN/Ag NWS bottom electrode, Ag NWS top electrode, PEDOT:PSS hole transport layer, etc. It was showed that PC71BM Electron transport layer, PEI modified layer and CH3NH3PbI3 perovskite film with high density and good uniformity can be obtained. We have fabricated CH3NH3PbI3 perovskite solar cells with area of 120 cm2, 150 cm2 and 180 cm2 respectively. The results show that the power conversion efficiency of the perovskite solar cell with effective area of 120 cm2 is as high as 16.78% (VOC = 1.02 V, JSC = 21.96 mA/cm2, FF = 75%; 150 cm2: 12.56%, 180 cm2: 10.68%), which is the highest efficiency reported so far. In addition, when the device is placed in the air for six months without packaging, the photoelectric conversion efficiency is reduced to 90% of the initial value. However, the photoelectric conversion efficiency of CH3NH3PbI3 perovskite solar cells with Fluorinated thermoplastic polyurethane film (FTPU) package is only reduced by 5%, which shows excellent device stability.

With the rapid development of perovskite solar cells (PSCs), PSCs without electron transport layer (ETL) structure have been reported one after another, but the efficiency is low. In this work, a tin-based ETL-free structure of perovskite solar cell is introduced. In order to explore the internal influencing factors of the device with ETL-free structure, we used SCAPS-1D (Solar Cells Capacitance Simulator) to simulate the device and adjust the appropriate physical parameters to approximate the results reported in the experiment. The simulation results show that the thickness of the absorption layer, defect density, operating temperature and band gap have different effects on the performance of the device, and the best absorbent layer thickness is 600 nm. When the operating temperature exceeds 300 K, the performance parameters will decrease, and the band gap is best controlled at about 1.3 V. It should be pointed out that defect density is the main culprit that seriously affects device performance. When defect density exceeds 1015cm−3, power conversion efficiency (PCE) begins to decline significantly, and we need to pay more attention to defect density. At the same time, the effects of different interface defect layers (IDL) on device performance are simulated. It is found that when the defect density of the interface defect layer is too high, the asymmetry effect will appear. The interface defect layer IDL2 between the absorption layer and the hole transport layer (HTL) has a greater effect on the open circuit voltage (VOC), and the interface defect layer IDL1 has a greater effect on PCE. Therefore, it is necessary to pay attention to these defect layers to improve the VOC and PCE. Finally, based on ETL-free PSCs, we list HTL of different materials for reference, and provide new ideas for perovskite solar cells in the future.

Due to the inherent moisture instability problem of hybrid lead halide perovskites, polymer additives have to turn out to be a significant research area to enhance the moisture stability of these materials. It has been found that polymer engineering on the absorber layer of solar cells significantly improves chemical stability and overall device performance. This work reports the fabrication of pristine and polyvinylpyrrolidone (PVP) polymer capped methylammonium lead chloride (CH3NH3PbCl3) perovskite film via the electrospinning method. A structural study using an X-ray diffractometer shows a sharp fall in average crystallite size from 66.05 nm to 39.69 nm when PVP is used in the synthesis procedure. A similar trend is also seen in the microscopic analysis, which depicts that the particle size has decreased for PVP added CH3NH3PbCl3 perovskite film in comparison to CH3NH3PbCl3 pristine film. The surface coverage and uniformity of the film is much more in the presence of PVP. It has been noted from energy dispersive X-ray analysis that the oxygen content is ∼16% more in the pure film, i.e. PVP hinders the effect of moisture in perovskite film, which is the prime objective of this work. Moreover, the optical properties have been analyzed using diffuse reflectance mode of UV–Vis-NIR spectroscope. Finally, the use of CH3NH3PbCl3 as the electron transport layer has been demonstrated in Glass/FTO/CH3NH3PbCl3/CH3NH3SnI3/Spiro-OMeTAD/Au structured perovskite solar cell using the SCAPS-1D simulator. The above-mentioned cell exhibits a power conversion efficiency (PCE) of 21.65%, fill factor (FF) of 72.21%, 32.44 mA/cm2 of short circuit current density (Jsc), and 0.924 V open-circuit voltage (Voc).

High-performance perovskite solar cells (PSCs) are readily degradable by moisture, leading to high demand for a water-repelling efficient hole transport layer (HTL). In this study, we proposed an a...

Perovskite/Silicon (PS) tandem solar cells have attracted much interest over recent years. However, the most popular crystalline silicon solar cells utilized in tandems require complicated fabrication processes mainly including texturization, diffusion, passivation and metallization, which takes up much cost in photovoltaic market. Here, we report a facile graphene/silicon (Gr/Si) solar cell featuring of low-temperature (≤ 200 ℃) processing and an efficiency of 13.56%. For reducing the heat dissipation loss of high energy photon, the perovskite solar cell (PSC) with a wide band gap of 1.76 eV was adopted as the top cell for the tandem. To reduce the loss of parasitic absorption in hole transport layers (HTLs), thickness of Spiro-OMeTAD is re-optimized by compromising the efficiency and the optical transmittance of the devices. As a result, the semitransparent top perovskite solar cell yields a highest efficiency of 13.35%. Furthermore, we firstly achieved a low-temperature-processed four-terminal (4-T) perovskite/graphene-silicon (PGS) heterojunction tandem solar cell with the efficiency of 20.37%. The levelized cost of electricity (LCOE) of PGS 4-T modules were estimated to a competitive price, exhibiting much greater potential for practical application compared to that of PS 4-T modules.

The use of renewable resources including solar energy has become a mandatory approach to reduce the repercussions of the excessive use of fossil fuels. Recently, there has been an exponential increase in the research of solar cells of various types, which led to their storming the international economic market as a safe source of energy. Silicon-based solar cells (Si-based SCs) occupied the throne of solar cells until the advent of perovskite solar cells (PSCs), which captured the attention of scientists around the world with its high and rapid tide in the values of their efficiencies, which exceeds 25% and predicted to reach the Shockley–Queisser limit. This review takes, in summary, a general tour in the world of PSCs to discuss the perovskite emergence and its composition materials, the components of PSCs, the unique properties of hybrid organic–inorganic perovskites (HOIPs) that stand behind the high-performance devices, the PSC architectures and their fabrication processes, the industrial challenges and finally a future view on PSC fate.

Lead (Pb) free (non-toxic) perovskite solar cells materials have attracted great interest in the commercialization of the photovoltaic devices. In this work, density functional theory (DFT) and linear response time-dependent within density functional theory (TDDFT) are used to simulate and investigate the effect of gold (Au) dopedPb-free double halide perovskite A2BB?X6(A = Cs; B = In, Au; B? = Sb; X = Cl) on the structural, electronic, and optical properties for perovskite solar cell application. On the structural properties, bond length and bulk modulus calculations show that the doped compound is more likely to resist deformation than the undoped compound. The calculated band structure for both materials (doped and undoped) reveals the presence of the Valence Band Maximum (VBM) and the Conduction Band Minimum (CBM) at around the same symmetry point which indicates a direct band gap nature (at ???? point). The band gap value for the initial compound (= 0.99 eV) agrees with published theoretical values. For the gold doped compound, the value of the band gap increased to a value of 1.25eV. The result of the optical properties shows that the Au-doped material has higher absorption coefficient, lower reflectivity and higher optical conductivity when compared with the initial, as such demonstrates better properties as a candidate for solar cell applications and in other optoelectronic devices.

Recently, low-dimensional Ruddlesden-Popper (LDRP) perovskite-based solar cells (PSCs) have been extensively studied because of their robust stability. However, because of the poor conductivity of the organic spacer, the charge transport across the spacers in the LDRP perovskite is considerably poor, and thus regulation of the growth orientation of LDRP cells is of primary importance. So far, the key role of organic cations in controlling the growth orientation of LDRP films has been widely studied, but the impact of halogens has not been sufficiently investigated. Herein, we demonstrate the important role of halogens in determining the characteristics of benzylamine (BZA)-based LDRP perovskite films, where different BZAX salts (X = Cl, Br, I) are adopted. Compared to Br and I, Cl is shown to prominently enlarge the grain size, promote the vertical orientation, reduce the trap state density, and prolong the carrier lifetime of LDRP film, and all these merits effectively accelerate the carrier transport within the film. As a result, a PSC device based on BZACl delivers a champion PCE of 17.25% with much improved device stability. This work unravels the vital role of Cl in regulating the crystallization process of LDRP films, which provides a facile approach for boosting the performance of LDRP-based PSCs.