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A molten-salt-assisted crystallization (MSAC) strategy is developed to improve the grain growth of all-inorganic perovskite films. MSAC enables more active mass transfer and interaction among precursor colloids. Devices based on the MSAC strategy show much increased efficiency to as high as 19.83% with open-circuit voltage as high as 1.2 V.

Abstract

Dynamic manipulation of crystallization is pivotal to the quality of polycrystalline films. A molten-salt-assisted crystallization (MSAC) strategy is presented to improve grain growth of the all-inorganic perovskite films. Compared with the traditional solvent annealing, MSAC enables more intensive mass transfer by means of convection and diffusion, which is beneficial to the interaction among the precursor colloids and to inducing in-plane growth of perovskite grains, resulting in the formation of high-quality perovskite films with suppressed pinhole and crack formation. Additionally, the introduction of molten salt alters the intermediate phases, and thus changes the crystallization pathways by reducing the energy barrier to produce films with desired optical and electrical properties. As a result, the MSAC strategy endows the devices with champion steady-state output efficiency of 19.83% and open-circuit voltage (V _oc) as high as 1.2 V, among the highest for this type of solar cell, thanks to its effectively reduced V _oc deficit.

Electro-strictive strain in 3D polycrystalline perovskite is observed, which can lead to an accelerated ion migration under operational conditions. The 1D–3D perovskite, that is, 1D BnPbI₃ perovskite, spatially distributed in the 3D perovskite film and compensating the dangling bonds in the grain boundaries, can effectively inhibit electro-strictive responses and unbalanced charge carrier extraction, realizing ultralong operational stability.

Abstract

3D organic–inorganic hybrid halide perovskite solar cells (pero-SCs) inherently face severe instability issue due to ion migration under operational conditions. This ion migration inevitably results from the decomposition of ionic bonds under lattice strain and is accelerated by the existence of excess charge carriers. In this study, a 1D–3D mixed-dimensional perovskite material is explored by adding an organic salt with a bulk benzimidazole cation (Bn⁺). The Bn⁺ can induce 3D perovskite crystalline growth with the preferred orientation and form a 1D BnPbI₃ perovskite spatially distributed in the 3D perovskite film. For the first time, the electro-strictive response, which has a significant influence on the lattice strain under an electric field, is observed in polycrystalline perovskite. The 1D–3D perovskite can effectively suppress electro-strictive responses and unbalanced charge carrier extraction, providing an intrinsically stable lattice with enhanced ionic bonds and fewer excess charge carriers. As a result, the ion migration behavior of the p-i-n 1D–3D based pero-SC is dramatically suppressed under operational conditions, showing ultra-long-term stability that retains 95.3% of its initial power conversion efficiency (PCE) under operation for 3072 h, and simultaneously achieving an excellent PCE with a hysteresis-free photovoltaic behavior.

A poling process that simultaneously modulates the built-in field and interface barriers of the perovskite solar cells has been conducted for the perovskite doped by P(VDF-TrFE). It has been unveiled that the new devices have achieved a high power conversion effectivity of 22.1%, attributed to the piezophototronic effect that effectively enhances the performance of the perovskite solar cell.

As a candidate for next-generation solar devices, perovskite solar cells are increasingly being studied for their rapid increased power conversion efficiency (PCE). One of the possible routes to further increase PCE is the introduction of polarization in the absorption layer which functions as a method for increasing the built-in potential and reducing the interface barrier, leading to much improved carrier separation and extraction. This technique uses the principle of the piezophototronic effect utilized for obtaining enhanced optoelectronic performances. Herein, to introduce internal polarization while maintaining optical absorption performance of the perovskite, organic–inorganic hybrid perovskite composite film solar cells are fabricated by doping polarized polyvinylidenefluoride-co-trifluoroethylene (P(VDF-TrFE)) into the perovskite. The composite film is polarized with an external potential, subsequently inducing the piezophototronic effect to enhance the performances of perovskite solar cells. Experimental results show that this simple polarization method has effectively improved several key characteristics of the solar cell. The PCE has reached up to 22.1%, the short-circuit current (J _sc) increases to 24.2 mA cm⁻², and the open-circuit voltage (V _oc) increases to 1.18 V.

One-step antisolvent-free hot-coating method is successfully used to fabricate Sn–Pb perovskite solar cells (PSCs) for the first time. Multiple cations are introduced to control the crystallization of the Sn–Pb film which produces PSCs with a champion power conversion efficiency over 15% and robust shelf stability. A novel ecofriendly approach for the fabrication of Sn–Pb PSCs is provided.

Pb-based perovskite solar cells (PSCs) have shown great potential in next-generation photovoltaics. However, the toxicity of Pb remains a big concern. Partial replacement of Pb with Sn is shown to reduce the toxicity of PSCs without considerably compromising the device performance. Currently, Sn–Pb single-junction PSCs have realized a champion power conversion efficiency (PCE) of 21.7%, whereas all perovskite tandem PSCs with a Pb–Sn device as the bottom cell have achieved a PCE of 25.5%. However, the fabrication process of Sn–Pb PSCs is still not ecofriendly due to the use of hazardous organic solvents and antisolvents. Herein, for the first time, a one-step antisolvent-free method is developed to fabricate a high-quality Sn–Pb perovskite film using methylammonium acetate (MAAc) ionic liquid as a green solvent. The crucial effects of multiple organic halides (MOHs) on the crystallization process and characteristics of the Sn–Pb film are comprehensively investigated. After optimizing the film fabrication parameters, PSCs with a champion PCE of 15.42% can be achieved. Moreover, the device exhibits robust stability that shows negligible PCE loss after being stored in N₂ for 720 h. A new avenue to promote the ecofriendly fabrication of efficient Sn–Pb PSCs is opened up.

A low defect halide perovskite film can be fabricated using trimethyl phosphate (TMP). TMP directly forms perovskite without intermediate phase due to weak Lewis basicity. The TMP-based film reduces hysteresis in current-voltage curve of perovskite solar cell. The TMP-based device exhibits better performance (>20%) than other solvent-based ones.

Abstract

Solvent engineering by Lewis-base solvent and anti-solvent is well known for forming uniform and stable perovskite thin films. The perovskite phase crystallizes from an intermediate Lewis-adduct upon annealing-induced crystallization. Herein, it is explored the effects of trimethyl phosphate (TMP), as a novel aprotic Lewis-base solvent with a low donor number for the perovskite film formation and photovoltaic characteristics of perovskite solar cells (PSCs). As compared to dimethylsulfoxide (DMSO) or dimethylformamide (DMF), the usage of TMP directly crystallizes the perovskite phase, i.e., reduces the intermediate phase to a negligible degree, right after the spin-coating, owing to the high miscibility of TMP with the anti-solvent and weak bonding in the Lewis adduct. Interestingly, the PSCs based on methylammonium lead iodide (MAPbI₃) derived from TMP/DMF-mixed solvent exhibit a higher average power conversion efficiency of 19.68% (the best: 20.02%) with a smaller hysteresis in the current-voltage curve, compared to the PSCs that are fabricated using DMSO/DMF-mixed (19.14%) or DMF-only (18.55%) solvents. The superior photovoltaic properties are attributed to the lower defect density of the TMP/DMF-derived perovskite film. The results indicate that a high-performance PSC can be achieved by combining a weak Lewis base with a well-established solvent engineering process.

Towards stable solar cells, ferrocene as a perpetual recovering agent has been developed to fix all elemental defects in ABX₃ perovskite by a chain-reaction cycle. The ferrocene cations can form a 1D perovskite structure which has suitable dissociation energy to convert back to light-harvesting 3D perovskite and reactivate its photovoltaic performance. Based on this recovering agent, perovskite solar cell can achieve >10 000 h lifetime.

Abstract

Lead halide perovskites always emerge complex interactions among different elemental ions, which lead to multiple intrinsic imperfections. Elemental defects, such as amine, Pb, and I vacancies at A-, B-, and X-sites, are main issues to deteriorate perovskite solar cells (PSCs). Unfortunately, most previous passivators can only temporarily fix partial inactive vacancies as sacrificial agents. Herein, we propose a recovery agent, ferrocene (Fc), which can form a one-dimensional perovskite with adequate steric cavities and suitable dissociation energy to recover all elemental defects back to active light-harvesting perovskites, and regenerate Fc itself meanwhile. Based on this perpetual chain-reaction cycle, corresponding PSCs maintain >10 000-hour lifetime in inert condition and >1000-hour durabilities under various extreme environments, including continuous 85 °C heating, 50 % relative humidity wetting, and 1-sun light soaking.

Near-infrared (NIR) photoactive semiconductor quantum dots (QDs) play a critical role for designing efficient wide-spectrum solar cells. This review provides a comprehensive analysis of the latest achievements of NIR QDs used for solar cells, including the classification of QDs and their photovoltaic performance, various strategies for performance improvements, and the challenges and perspectives for the future advances.

Abstract

Semiconductor quantum dots (QDs) are nanocrystals whose excitons are bound in 3D space. Owning to their remarkable quantum confinement effect, QDs exhibit a discontinuous electronic energy level structure similar to that of atoms, leading to novel physical, optical, and electrical properties for various optoelectronic device applications including solar cells. Near-infrared photoactive narrow bandgap (NBG) QDs can maximize the use of solar energy through the quantum size effect, offering a good opportunity for designing highly efficient wide-spectrum responsive solar cells. This review analyzes the recent research progress of NBG QDs as light absorbing materials in solar cells. The critical elaboration of the latest achievements both in material design and device optimization for NBG QD-based solar cells (QDSCs), including QD synthesis and film fabrication, design of device configuration, classification of NBG QDs and their photovoltaic performance, strategies for performance improvements is focused upon. The current challenges and perspectives for the further advance of NBG QDSCs are also discussed.

Gradual perovskite phase based on 2D cyclohexylmethylammonium iodide as the order of n and funnel-like energy level alignment during surface treatment with a simple solution process facilitates efficient charge transport electrically and improves power conversion efficiency from 20.41% to 23.91%.

Abstract

Insufficient charge extraction at the interfaces between light-absorbing perovskites and charge transporting layers is one of the drawbacks of state-of-the-art perovskite solar cells. Surface treatments and/or interface engineering are necessary to approach the Shockley–Queisser limit. In this work, novel 2D layered perovskites, such as CHA₂PbI₄ (CHAI = cyclohexylammonium iodide) and CHMA₂PbI₄ (CHMAI = cyclohexylmethylammonium iodide), are introduced in between 3D perovskites and hole transporting layers by a simple solution process and the 2D/3D perovskite heterojunction is formed and confirmed. Spontaneous photoluminescence quenching is observed by efficient hole extraction with a favorable valence band alignment. The charge extraction ability and recombination are directly measured by the transient photocurrent and photovoltage. Moreover, the interface resistance of the devices significantly is decreased to 30% as compared to devices without 2D perovskites. As a result, the devices with 2D/3D perovskite heterojunction exhibit improved power conversion efficiency (PCE) from 20.41% to 23.91% primarily because of the increased open-circuit voltage (1.079 to 1.143 V) and fill factor (78.22% to 84.25%). The results provide a detailed insight into hole extraction and high PCEs with the formation of a 2D/3D perovskite heterojunction.

Hole-Transporting Layers

In article number 2103807, Lydia Helena Wong and co-workers use Al-doped CuS as a hole transport layer (HTL) for perovskite solar cells. Here, it has been demonstrated that, due to the interaction between sulfur and lead, better perovskite crystallization takes place at the interface. Because of this improved interface quality, the sulfide-HTL based devices outperform the oxide HTL-based devices in terms of ambient stability.

A poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS)-free organic solar cell (OSC) architecture is successfully constructed by employing a binary solvent-chlorinated indium tin oxide anode, which can simultaneously improve the device performance and operational stability of non-fullerene OSCs.

Abstract

Despite the tremendous development of different high-performing photovoltaic systems in non-fullerene polymer solar cells (PSCs), improving their performance is still highly demanding. Herein, an effective and compatible strategy, i.e., binary-solvent-chlorinated indium tin oxide (ITO) anode, is presented to improve the device performance of the state-of-the-art photoactive systems. Although both ODCB (1,2-dichlorobenzene) solvent- and ODCB:H₂O₂ (hydrogen peroxide) co-solvent-chlorinated ITO (ITO-Cl_-ODCB and ITO-Cl_-ODCB:H2O2) show similar optical transmittance, electrical conductivities, and work function values, ITO-Cl_-ODCB:H2O2 exhibits higher Cl surface coverage and more suitable surface free energy close to the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-buffered ITO anode (ITO/PEDOT:PSS). As a direct consequence, the performance of ITO-Cl_-ODCB-based PBDB-T-2F:BTP-eC9:PC₇₁BM PSCs is comparable as the bare ITO-based devices. In contrast, the performance of ITO-Cl_-ODCB:H2O2-based devices with both small and the scaled-up areas significantly surpass the ITO/PEDOT:PSS-based devices. Furthermore, detailed experimental studies are conducted linking optical property, blend morphology, and physical dynamics to find the reasons for the performance difference. By applying the ITO-Cl_-ODCB:H2O2 anode to six other photovoltaic systems, the device efficiencies are enhanced by 3.6–6.2% relative to those of the ITO/PEDOT:PSS-based control devices, which validates its great application potential of co-solvent-modified ITO anode employed into PEDOT:PSS-free PSCs.

Incorporation of the chromium-based metal–organic framework as an A-site cation allows realizing a new multiple-dimensional electronically coupled CsPbI₂Br perovskite, which is theoretically and experimentally proved to improve the carrier transport ability and stability of perovskite solar cells (PSCs). Consequently, the as-fabricated CsPbI₂Br PSCs demonstrate 17.02% power conversion efficiency while superior long-term stability.

Abstract

Inorganic CsPbI _x Br_{3− x} perovskite solar cells (PSCs) have gained enormous interest due to their excellent thermal stabilities. However, their intrinsically poor moisture stability hampers their further development. Herein, a chromium-based metal–organic framework group is intercalated inside the inorganic PbI framework, resulting in a new multiple-dimensional electronically coupled CsPbI₂Br perovskite. In this structurally and electronically coupled perovskite, the π-conjugated terpyridyl can delocalize the excited valence electrons of metal Cr³⁺ ion, enabling multi-interactive charge-carrier transport channels within CsPbI₂Br perovskites. The stability and efficiency of the produced devices are substantially enhanced in comparison to their counterparts with only a pristine CsPbI₂Br active layer. The optimized all-inorganic PSC yields a power conversion efficiency (PCE) as high as 17.02%. Remarkably, the stabilized device retains 80% of its PCE after 1000 h in the ambient atmosphere. This study provides a new paradigm toward addressing the stability challenge of the inorganic perovskite while enhancing its carrier transport ability.

A novel fullerene molecular template with a solubility enhancer arm (R1) and a π–π interaction inducer arm (R2) is deliberately proposed. This design effort delivers the highest power conversion efficiency over 20% of the device with corresponding fulleropyrrolidine electron transport material for the first time.

Abstract

[6,6]-phenyl-C₆₁-butyric acid methyl ester remains indispensable as the electron transport material (ETM) for perovskite solar cells (PSCs), but its synthesis involves complicated multisteps with low productivity. In contrast, the potential of synthesizing simpler fulleropyrrolidine derivatives has long been overlooked, and little has been understood regarding their structure-dependent effects on photovoltaic (PV) performance. Herein, seven novel fulleropyrrolidine derivatives (F1–F7) are deliberately designed, synthesized, and comprehensively characterized in both solution and thin-film states and subsequently investigated as ETMs for PSCs. Notably, the F4 delivers the highest power conversion efficiencies over 20% of devices, which surpass all reported fulleropyrrolidine ETMs due to its optimal photoelectric property. Moreover, the structure-dependent effects of the fullerenes on PV parameters are uncovered, including solubility, intermolecular interaction, packing structure, and charge-transfer ability, which can guide the future design of high-performance and stable fullerene ETMs for PSCs.

A power conversion efficiency of 12.91% and an average visible transmittance of 22.49% are achieved in semitransparent organic photovoltaics (OPVs) with D18:N3 (0.7:1.6, wt/wt) as active layers. This work demonstrates that the wide bandgap polymer donor with narrow photon harvesting in the visible light range has great potential in preparing efficient semitransparent OPVs.

Abstract

Wide bandgap polymer D18 with narrow photon harvesting in visible light range and small molecule N3 with near-infrared photon harvesting are adopted for building semitransparent organic photovoltaics (OPVs). To find out the optimal D18:N3 weight ratio for semitransparent OPVs, series of opaque OPVs are built with a varied D18:N3 weight ratio. The power conversion efficiency (PCE) and fill factor can be maintained over 16% and 77% in the D18:N3 (0.7:1.6, wt/wt) based opaque OPVs, respectively. The average visible transmittance (AVT) of the corresponding blend films can be achieved over 50%, demonstrating the great potential in fabricating efficient semitransparent OPVs. The semitransparent OPVs based on D18:N3 (0.7:1.6, wt/wt) are fabricated by using 1 nm Au/(10, 15, 20 nm) Ag as cathode. The thickness of Ag layers is varied to balance the optical properties and electrical properties of semitransparent top electrode. The semitransparent OPVs with 10 nm Ag achieve the highest light utilization efficiency of 2.90% with a PCE of 12.91% and an AVT of 22.49%, which should be among the best performance of reported semitransparent OPVs. This work demonstrates that the wide bandgap polymer donor with narrow photon harvesting in visible light range has great potential in preparing efficient semitransparent OPVs.

A bulky low-work function (low-WF, 4.1 eV) PEDOT:PSS-TBA is presented via ion exchange. Superior to other low-WF materials, the PEDOT:PSS-TBA is stable under oxygen plasma, heat, or isopropanol sonication. By combining the low-WF PEDOT:PSS-TBA and high-WF PEDOT:PSS as the cathode and anode, respectively, as a proof of concept, organic solar cells with a three-layered structure (PEDOT:PSS-TBA/PM6:IT-4F/PEDOT:PSS) are demonstrated.

Abstract

Cathode with low work-function (WF) is a vital unit in optoelectronic devices. Yet, the stable cathode is still a big challenge. Here, PEDOT:PSS-TBA is reported among series of PEDOT:PSS-M, where PEDOT:PSS denotes poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), M refers to monovalent cation and TBA is tetrabutylammonium specifically, as a stable cathode. The PEDOT:PSS-TBA is synthesized via ion exchange with WF of 4.1–4.2 eV and its conductivity can be improved to 300 S cm⁻¹ by the additive. Meanwhile, PEDOT:PSS-TBA is stable even under plasma, heat, or isopropanol sonication. Organic solar cells (OSCs) are fabricated with indium tin oxide (ITO)/PEDOT:PSS-TBA and highly conductive PEDOT:PSS-TBA (with additive, hc-PEDOT:PSS) electrodes respectively. The OSCs display superior stability than the reference with ITO/ZnO as the cathode. As a proof of concept, solution-processed OSCs are demonstrated with a three-layered structure (hc-PEDOT:PSS-TBA/active layer/PEDOT:PSS), which proves PEDOT:PSS-TBA as a promising cathode for printable optoelectronic with a simplified structure.

Nature Materials, Published online: 16 September 2021; doi:10.1038/s41563-021-01097-x

The band-tailing and bandgap fluctuations in CZTSSe solar cells can be reduced through partially substituting Zn with trace Ba doping. When the doping ratio of Ba in CZTSSe is only 1%, the power conversion efficiency of the CZTSSe solar cells is noteworthily enhanced by 25.6%, due to the doping cation with large difference of the chemical coordination environment.

Being absent from larger mismatch of ionic radius and chemical coordination between the cations in Cu₂ZnSn(S,Se)₄ (CZTSSe) can aggravate the formation of detrimental cation antisite defects and clusters with low formation energy, which results in a serious open-circuit voltage deficit and a challenge for higher power conversion efficiency of CZTSSe solar cells. External cation doping or alloying is a more effective strategy to solve this issue. Herein, samples of trace Ba doping into CZTSSe are fabricated by the sol–gel method and the mechanism of such trace Ba doping are studied combined by X-ray diffraction (XRD), Raman, and photoluminescence (PL) measurements. The performance of CZTSSe solar cells is increased by 25.7% as 1% Ba is doped into CZTSSe to substitute Zn. The results highlight the roles of the trace Ba doping on the performance of CZTSSe solar cells, which is beneficial to the reduced formation of the detrimental defects and associated clusters. As a consequence, the bandgap fluctuations are reduced, which results in the improvement of V _OC and thus the performance of the solar cell. The cation substitution engineering with larger chemical mismatched alkaline-earth metal cations provides insights for further improvement of CZTSSe solar cells based on earth abundant elements.

The mechanosynthesized perovskite powder is used to fabricate films and solar cells by magnetron sputtering. The stable PSCs with excellent reproducibility show a PCE of up to 15.22%. This approach realizes solvent-free preparation of perovskite films with controllable composition, which would open up a promising way to achieve high-throughput magnetron sputtering for large-area production of planar heterojunction and tandem PSCs.

Abstract

Organic–inorganic halide perovskites have been widely used in photovoltaic technologies. Despite tremendous progress in their efficiency and stability, perovskite solar cells (PSCs) are still facing the challenges of upscaling and stability for practical applications. As a mature film preparation technology, magnetron sputtering has been widely used to prepare metals, metallic oxides, and some semiconductor films, which has great application potential in the fabrication of PSCs. Here, a unique technology where high-quality perovskite films are prepared via magnetron sputtering for controllable composition, solvent-free, large-area, and massive production, is presented. This strategy transforms the perovskite materials from powder to thin films by magnetron sputtering and post-treatment (vapor-assisted treatment with methanaminium iodide gas and methylamine gas treatment), which is greatly favorable to manufacture tandem solar cells. The power conversion efficiency (PCE) of PSCs with perovskite films fabricated by magnetron sputtering is 6.14%. After optimization, high-performance perovskite films with excellent electronic properties are obtained and stable PSCs with excellent reproducibility are realized, showing a PCE of up to 15.22%. The entirely novel synthetic approach opens up a new and promising way to achieve high-throughput magnetron sputtering for large-area production in commercial applications of planar heterojunction and tandem PSCs.

The multi-scale defect repair strategy is developed to fabricate scalable and flexible perovskite solar cells. By inhibiting the aggregation behavior of colloidal particles to avoid pinholes and intergranular cracking in the perovskite film, along with repairing the deep defects at the interface, the target flexible devices (1.01 cm²) deliver a superior efficiency of 18.12% with improved air atmosphere stability.

Abstract

Homogeneity and stability of flexible perovskite solar cells (PSCs) are significant for the commercial feasibility in upscaling fabrication. Concretely, the mismatching between bottom interface and perovskite precursor ink can cause uncontrollable crystallization and undesired dangling bonds during the printing process. Herein, methylammonium acetate, serving as ink assistant (IAS) can effectively avoid the micron-scale defects of perovskite film. The in situ optical microscope is applied to prove the IAS can inhibit the colloidal aggregation and induce more adequate crystallization growth, thus avoiding the micron-scale defects of pinholes and intergranular cracking. Concurrently, 4-chlorobenzenesulfonic acid is introduced into the electrode surface as a passivation layer to restore the deep traps at perovskite interface in nano-scale. Finally, the target flexible devices (1.01 cm²) deliver a superior efficiency of 18.12% with improved air atmosphere stability. This multi-scale defect repair strategy provides an integrated design concept of homogeneity and stability for scalable and flexible PSCs.

Publication date: December 2021

Source: Nano Energy, Volume 90, Part A

Author(s): Xiaoqing Jiang, Jiafeng Zhang, Yang Liu, Ziyuan Wang, Xuan Liu, Xin Guo, Can Li

The simple treatment of time and mild annealing of finished coevaporated perovskite solar cells leads to a substantial improvement in voltage and power conversion efficiency. By using transient electrical measurements combined with drift diffusion simulations, it is herein attested that the voltage improvement originates from an increased charge carrier lifetime, associated with a reduction of Shockley–Read–Hall trap-mediated recombination.

The photovoltaic perovskite research community has now developed a large set of tools and techniques to improve the power conversion efficiency (PCE). One such arcane trick is to allow the finished devices to dwell in time, and the PCE often improves. Herein, a mild postannealing procedure is implemented on coevaporated perovskite solar cells confirming a substantial PCE improvement, mainly attributed to an increased open-circuit voltage (V _OC). From a V _OC of around 1.11 V directly after preparation, the voltage improves to more than 1.18 V by temporal and thermal annealing. To clarify the origin of this annealing effect, an in-depth device experimental and simulation characterization is conducted. A simultaneous reduction of the dark saturation current, the ideality factor (n _id), and the leakage current is revealed, signifying a substantial impact of the postannealing procedure on recombination losses. To investigate the carrier dynamics in more detail, a set of transient optoelectrical methods is first evaluated, ascertaining that the bulk carrier lifetime is increased with device annealing. Second, a drift-diffusion simulation is used, confirming that the beneficial effect of the annealing has its origin in effective bulk trap passivation that accordingly leads to a reduction of Shockley–Read–Hall recombination rates.

The entry of perovskite solar modules into the photovoltaic market is limited by the large lab-to-fab gap in device efficiency. Herein, the limiting factors are analyzed and a brief overview on its fast development in module efficiencies fabricated by different film deposition methods is presented. Finally, opinions on the future development of perovskite solar modules are shared.

Metal halide perovskites are considered as game changers for future solar cell technology due to their rapidly increasing device efficiencies and potential for manufacturing at low cost. In view of their promising commercial potential, increasing research efforts are now dedicated to the development of large-area perovskite solar modules. Herein, the motivation for developing perovskite solar modules and the challenges to fabricate large-area perovskite solar cells with high efficiency are discussed. The important thin-film processing methods including solution-based and vacuum-based deposition technologies for scaling up the fabrication of perovskites are reviewed. In addition, other key challenges that need to be overcome to bring perovskite solar modules into photovoltaic (PV) markets are also discussed, including module stability, potential lead leakage issue, and outdoor field testing of the perovskite modules. Finally, opinions on the future development of perovskite PV modules are shared.