Semitransparent Perovskite Solar Cells Research Articles

Effect of sputtering pressure on the properties of large area IWO thin films deposited by direct current magnetron sputtering

Tungsten doped indium oxide (In2O3: W, IWO) thin films have been attracting increasing attention due to their excellent optoelectronic properties. Here, a series of IWO thin films were prepared using direct current (DC) magnetron sputtering method, by varying the sputtering pressure. Analysis revealed that the IWO films prepared under sputtering pressure of 0.4 Pa exhibited excellent optoelectronic performance, with low square resistance, resistivity, high carrier concentration and mobility. The resulting semi-transparent perovskite solar cells (ST-PSCs), with IWO fabricated under 0.4 Pa, yield a PCE of 15.71 % for the large area modules of 100 cm2 (active area 64.8 cm2).

In-situ defect passivation assisted three-step printing of efficient and stable formamidine-lead bromide solar cells

Perovskite solar cells (PSCs) emerge as the most promising photovoltaics (PV) for their high performance and potential convenient cost-effective production routes comparing to the sophomore PV technologies. The printed PSCs with simplified device architecture and fabrication procedures could further enhance the competitive strength of PSC technology. In this work, we present an in-situ defect passivation (ISDP) assisted full-printing of high performance formamidine-lead bromide (FAPbBr3) PSCs. Only three rapid printing steps are involved for electron transporting layer (ETL), perovskite and carbon to form a complete solar cell on the low-cost fluorine-doped tin oxide (FTO) substrate. Long-chain polymer monomethyl ether polyethylene glycol is particularly utilized as the ISDP passivator, leading to conformal coating on the rough FTO and defect passivation for both ETL and perovskite during printing. A high efficiency of 10.85% (certified 10.14%) and a high Voc up to 1.57 V are achieved for the printed device. The unencapsulated PSCs maintain above 90% of the initial efficiency after continuously heating at 85 °C for 1000 h and over 80% of the efficiency after the maximum power point tracking for 3500 h. The fully printed semitransparent PSCs with carbon grids (CGs) shows average visible light transmittance over 33% and an efficiency of 8.81%.

Ionic‐Rich Vermiculite Tailoring Dynamic Bottom‐Up Gradient for High‐Efficiency Perovskite Solar Cells

AbstractMixed‐halide perovskites are emerging as excellent photovoltaic candidates because of their tunable bandgaps for semitransparent and tandem perovskite solar cells. However, the notorious film quality originated from the rapidly downward crystallization process susceptibly propagates enormous detrimental defects, which deteriorate the photovoltaic performance and accelerate halide segregation. To address this issue, herein, a multilayer alkalis‐intercalated‐vermiculite is employed as pre‐buried interface modifier to regulate the perovskite lattice property. The matchable lattice structure between perovskite and vermiculite by forming Pb─O bond not only releases the interfacial strain during the film growth but also the embedded alkalis ions can gradually diffuse into perovskite lattice to form a favorable vertical gradient owing to the weak interlamellar van der Waals interaction, playing bis‐roles of atomical lubricant and ion‐reservoir to eliminate detrimental defects. As a result, the film quality and lattice stability is significantly improved with suppressed phase segregation for mixed‐halide perovskites, accompanying a champion efficiency of 11.42% for carbon‐based CsPbIBr2 device, 15.25% for carbon‐based CsPbI2Br device and 23.17% for p‐i‐n inverted (Cs0.05MA0.05FA0.9)Pb(I0.93Br0.07)3 cell. This work provides a new strategy on buried interface engineering for making high‐efficiency and stable perovskite platforms.

Interface Reactive Sputtering of Transparent Electrode for High-Performance Monolithic and Stacked Perovskite Tandem Solar Cells.

Sputtered indium tin oxide (ITO) fulfills the requirements of the top transparent electrodes (TTEs) in semitransparent perovskite solar cells (PSCs) and stacked tandem solar cells (TSCs) as well as the recombination layers in monolithic TSCs. However, the high-energy ITO particles will cause damage to the devices and reduce the photovoltaic performance. Herein, the interface reactive sputtering strategy has been proposed and implemented to construct cost-effective TTEs with high transmittance and excellent carrier transporting ability, aiming to realize high-performance semitransparent and tandem PSCs. Polyethylenimine (PEI) was chosen as the interface reactant, of which abundant amino groups on PEI can react with sputtered ITO nanoparticles so that coordination compounds can be formed during the ITO deposition process, facilitating the carrier transport at the interface of C60/PEI/ITO. Besides, the impact force of energetic ITO particles is greatly alleviated, and the intactness of the underlying C60 layer and perovskite layer is guaranteed. Thus, the prepared semitransparent subcells achieve a significantly enhanced power conversion efficiency (PCE) of 19.17%, surpassing those based on C60/ITO (11.64%). Moreover, the PEI-based devices demonstrate excellent storage stability, which maintains 98% of their original PCEs after 2000 hours. On the strength of the interface reactive sputtering ITO electrode, we successfully fabricated a stacked all-perovskite TSC with a PCE of 26.89% and a monolithic perovskite-organic TSC with a PCE of 24.33%. This work has provided a facile and instrumental solution for rendering TTEs function well in semitransparent and tandem PSCs. This article is protected by copyright. All rights reserved.

Research Progress of Semi-Transparent Perovskite and Four-Terminal Perovskite/Silicon Tandem Solar Cells

Perovskite/silicon tandem solar cells are of great interest due to their potential for breaking the Shockley-Queisser limit of single-junction silicon solar cells. Perovskite solar cells are widely used as the top subcells in perovskite/silicon tandem solar cells due to their high efficiency and lower fabrication cost. Herein, we review the semi-transparent perovskite solar cell in terms of the mechanisms of their translucent structure, transparent electrodes, charge transport layer, and component modification. In addition, recent progress in the research and development of 4T perovskite/silicon tandem solar cells is summarized, with emphasis on the influence of perovskite structure and silicon cells on the progress of tandem solar cells. Finally, we discuss the challenges associated with 4T perovskite/silicon tandem solar cells and suggest directions for the development of perovskite/silicon commercialization.

Green Material Chlorin e6 Passivation Improves the Efficiency of Perovskite Solar Cells

Functional passivation agents have been shown to effectively optimize the crystallization process and passivate defects on the surface and grain boundaries. People have conducted extensive research on the passivation mechanisms of various passivation agents to obtain more effective passivation agents. Researchers are gradually focusing on natural ingredients in the search for suitable passivation agents due to the wide variety, green colour, and ease of production. As a result, we first combined the natural chlorophyll component chlorin e6 (CE‐6) with perovskite solar cells to improve their performance. Following the incorporation of CE‐6 into the perovskite layer, various functional groups of CE‐6 are used to effectively reduce traps on the perovskite surface, suppress charge recombination at the interface, improve carrier transfer rate and carrier extraction efficiency, and ultimately improve efficiency. The optimal device achieved a power conversion efficiency (PCE) of 21.14% and maintained its initial PCE of 84% after being stored in a room‐temperature air environment for 500 hours. Furthermore, semi‐transparent perovskite solar cells (ST‐PSC) was made with 13.33% PCE, and 5.53% average visible light transmittance (AVT). Our findings show that natural material CE‐6 performs well in the perovskite layer and confirms the promising prospects for optimizing semi‐transparent PSC.This article is protected by copyright. All rights reserved.

Doping with KBr to Achieve High-Performance CsPbBr3 Semitransparent Perovskite Solar Cells.

Wide-bandgap semitransparent perovskite photovoltaics are emerging as one of the ideal candidates for building-integrated photovoltaics (BIPV). However, surface defects in inorganic CsPbBr3 perovskite prepared by vapor deposition severely limit the optoelectronic performance of perovskite solar cells. To address this issue, a strategy of doping a trace amount of KBr into perovskite by vapor deposition is adopted, effectively improving the quality of the film, reducing surface defect concentration, and enhancing the transportation and extraction of charge carriers. Simultaneously, fully physical vapor deposition technology is employed to fabricate perovskite solar cells with an average visible light transmittance of 44%. These devices exhibited an ultrahigh open-circuit voltage of 1.55 V and a superior power conversion efficiency (PCE) of 7.28%, demonstrating excellent moisture and heat resistance. Moreover, the corresponding 5 cm × 5 cm modules achieve a PCE of 5.35% with great thermal insulation capability. This work provides an approach for fabricating highly efficient all-inorganic perovskite solar cells with high average visible light transmittance, demonstrating new insights into their application in building-integrated photovoltaics.

Influence of the electron transport layer coating technique on sputter damage and its curing in inverted semi-transparent perovskite solar cells without protective buffer layer

In semi-transparent perovskite solar cells (PSCs) comprising a sputtered top electrode, the minimisation of detrimental sputter damage and/or its curing by post-processing treatment is essential to reach high efficiencies. In this work, we investigate the influence of sputter damage and post-deposition annealing steps for different electron transport layers (ETLs) in PSCs without the need of a protective buffer layer such as tin oxide deposited by atomic layer deposition. We compare solution-processed 6,6-Phenyl C61 butyric acid methyl ester (PCBM) to thermally evaporated C60, each in combination with a bathocuproine (BCP) layer deposited by spin coating or thermal evaporation including a thickness variation. In general, we find that C60 is more resilient against sputter damage and thus C60-based cells show higher as-grown power conversion efficiencies (PCEs). Post-deposition annealing of the complete cell stack increases the PCE further to values > 16 % on 0.5 cm2 active area. However, we observe that the remaining solvent in the spin-coated PCBM layer is highly beneficial for the curing of the sputter damage during post-deposition annealing and we achieve even higher PCEs for cells incorporating solution-processed PCBM with up to > 18 % on 0.5 cm2. We show an alternative way to reach high efficiency semi-transparent perovskite solar cells without using thermally evaporated C60 and/or a buffer layer like tin oxide deposited by atomic layer deposition (ALD).

Controlled Fabrication of Composite Transparent Electrodes for Semitransparent Perovskite Solar Cells with above 84% Fill Factor

In the quest to develop efficient semitransparent perovskite solar cells (ST‐PSCs), the primary challenge lies in transparent electrode fabrication. n–i–p‐type ST‐PSCs often suffer from low fill factors (FF) and power conversion efficiency (PCE), attributed to the undesirable buffer layer/transparent conductive oxide combination of the transparent electrode. In this context, this study proposes an efficient composite transparent electrode (CTE) system comprising an ultrathin MoO3 buffer layer (5 nm) and low‐power sputtered indium zinc oxide (45 W–220 nm). The electrode demonstrates excellent compatibility with Spiro‐OMeTAD‐based devices, effectively addressing the low FF and PCE challenges of ST‐PSCs. Employing the new CTE, the best‐performing ST‐PSCs with the absorption edge at 1.57 eV achieve a remarkable PCE of 21.96% with an FF of up to 83.80%. More transparent ST‐PSCs with thickness‐modulated absorbers and average transmittance of 50.77% at 600–1200 nm wavelength result in a PCE of up to 20.91% with the highest known FF of 84.02%. This study presents a general and viable approach for fabricating efficient ST‐PSCs.

Revealing the Hole and Electron Transport Dynamics in the Working Devices for Efficient Semitransparent Perovskite Solar Cells

AbstractThe performance and stability of perovskite solar cells (PSCs) are dominated by the electron and hole transport dynamics, which are highly desired to be characterized in the working devices. Nevertheless, for the opaque PSCs, the hole transport layer (HTL) in n–i–p devices or the electron transport layer (ETL) in p–i–n devices are typically buried beneath the metal electrode, which makes it difficult to simultaneously characterize the charge transport dynamics from both sides of the working devices. In this work, for the first time, the charge transport dynamics of the working devices from both the front and rear side of semitransparent PSCs (ST‐PSCs) is characterized via femtosecond transient reflection spectroscopy (FS‐TRS). A significant enhancement of the hole transport and negligible change of the electron transport is observed when the perovskite/HTL interface is treated by 2‐chloro‐phenethylammonium iodide (2‐Cl‐PEAI). A champion power conversion efficiency (PCE) of 23.3% (certified 22.3%) is achieved, which is the highest certified PCE for ST‐PSCs up to date. The ST‐PSCs maintained more than 90% of its initial efficiency after 2000 h of maximum power point tracking (MPPT). Additionally, the ST‐PSCs are implemented in 4‐terminal (4‐T) perovskite/passivated emitter rear silicon cell (PERC), reaching a simulated output power of 30.8 mW cm−2.

Revealing the stability origins of 596 days-humidity-stable semitransparent perovskite solar cells

Hybrid organic–inorganic perovskites (HOIPs) hold promise in the field of optoelectronics due to their excellent photoelectric conversion efficiency. However, the ion migration and hygroscopicity of these perovskite solar cells need to be addressed. Here, we presented semitransparent perovskite solar cells (ST-PSCs) using hole transport layer (HTL) combined with polyaniline (PANI) to stabilize HTL/perovskite interface, achieving a humidity durability (RH, 50%–90%) for 596 days (14304 h) without encapsulation. Moreover, the decrease in hydrolysis products (LiF) showed the interaction between PANI with the additives in HTL dramatically inhibited the water uptake and corrosion on MAPbI3 layer. The PANI modified samples had a higher I/Pb ratio and lower trap state density, which indicated the passivation effect of PANI on the uncoordinated Pb2+ and iodine vacancies. Subsequently, PANI successfully stabilized the interface and perovskite by inhibiting the formation of Pb0 and Au migration as long period storage. This work presented an interfacial design to develop HOIP in air with high humidity stability.

Low-damage hydrogen-doped transparent electrodes towards semitransparent perovskite photovoltaics

As one kind of transparent conductive electrodes (TCEs), transparent conductive oxides (TCOs) have been widely used in perovskite solar cells (PSCs). However, the conventional magnetron sputtering usually causes high-energy particles, thus damaging the underlying functional films and deteriorating the performance of devices. Therefore, developing a low-damage method for high-quality TCO film is crucial. Here, the hydrogen and cerium co-doped indium oxide (ICO:H) films were prepared by the reactive plasma deposition (RPD) technology at room temperature. Benefiting from the hydrogen doping, the bandgap of the ICO:H film was tuned to 3.97 eV, the average transmittances reached 91.25% (from 800 nm to 1200 nm) and 81.35% (from 300 nm to 800 nm), and the carrier mobility exceeded 30 cm2/V/s. Combined with these advantages, semitransparent perovskite solar cells (ST-PSCs) without buffer layers were fabricated using ICO:H films as transparent conductive window layers, and the power conversion efficiency (PCE) was up to 17.61% (from the glass side). Furthermore, the ICO:H films were also applied in two-terminal perovskite/silicon tandem solar cells, and the PCE exceeded 25%. This low-damage method opens a new avenue for fabricating film-based optoelectronics.

Hot-Antisolvent Assisted Morphological Regulation of Perovskites for Semitransparent Photovoltaics Employing Hot-Pressing Approach

The processing of halide perovskites in the air significantly influences their morphology and surface coverage, often leading to the presence of numerous trap densities that adversely affect device performance. In this study, we explored the development of perovskite films using a solvent extraction method, where the temperature of the anisole antisolvent was varied. Our findings demonstrate that the hot-antisolvent strategy effectively controls nucleation, resulting in the formation of highly dense, pinhole-free, and crack-free perovskite films with reduced surface roughness. Films fabricated using this hot-antisolvent approach exhibited enhanced photoluminescence, indicating lower trap density and increased recombination resistance. They also showed slower charge carrier recombination rates and efficient charge extraction, suggesting the suppression of nonradiative recombination. Furthermore, the superior quality of perovskite films obtained through the hot-antisolvent strategy significantly enhanced the power conversion efficiency (PCE) of hot-pressed semitransparent perovskite solar cells. The PCE remarkably increased from 0.13% to an impressive 12.65% while maintaining an average visible transmittance of 26.55% and exceptional air stability for 2000 hours with no significant degradation in initial PCE. This study achieves a record-breaking light utilization efficiency of 3.36% in the realm of research on hot-press processes.

Efficient Bifacial Semitransparent Perovskite Solar Cells Using Down‐Conversion 2D Perovskite Nanoplatelets–Poly(Methyl Methacrylate) Composite Film

Semitransparent perovskite solar cells (ST‐PSCs) hold significant appeal for various applications in smart windows, multijunction tandem devices, bifacial and chargeable devices, etc. Unfortunately, to possess high transparency, the perovskite layer in the ST‐PSCs must be kept relatively thin (<400 nm), which in turn causes insufficient light absorption and thus inferior device performance. Herein, a 2D perovskite nanoplatelets (NPLs)/poly(methyl methacrylate) (PMMA) composite thin layer is applied in the ST‐PSCs to solve these problems. Thanks to its dual function of down‐conversion (DC) effect, converting high‐energy UV photons into low‐energy visible photons to enhance the photocurrent, and interfacial passivation, reducing the nonradiative recombination at the interface, the 2D NPLs–PMMA‐based devices with the different average visible transmittance (AVT) values of perovskite film demonstrate significantly improved power‐conversion efficiency (PCE) compared to the pristine devices, and remarkable UV stability, retaining over 77% of initial PCE after aging under continuous UV illumination for 280 h. More importantly, the full bifacial ST‐PSCs using a transparent MoO3/Au/MoO3 rear electrode exhibits a record PCE of 14.26% and 10.65% with a whole device AVT of 19.4% and 26.9%, respectively, which are among the highest performing ST‐PSCs of the kind reported to date.

Structurally colored semitransparent perovskite solar cells using one-step deposition of self-ordering microgel particles.

Semitransparent perovskite solar cells (STPSCs) have excellent potential for widespread application as building integrated photovoltaics. Widespread application of STPSCs could result in decreased CO2 footprints for buildings. Unfortunately, STPSCs tend to have poor aesthetic qualities (being usually red-brown in color) and low stability. Building on our previous work, here we use new poly(N-isopropylacrylamide) microgels (PNP MGs) to provide highly ordered non-close packed arrays within perovskite films that reflect some of the incident light to provide structural color to STPSCs. (MGs are swellable crosslinked polymer colloid particles.) We introduce PNP MGs into two different perovskites and achieve a wide gamut of reflected color and iridescence from the perovskite films. Devices containing the MGs have average visible transparency (AVT) values of greater than 25%. The best PCE for a MG-containing STPSC is 10.60% compared to 9.14% for the MG-free control. The MGs not only introduce structural color to the STPSCs but increase the PCE and stability. Equations are provided that enable the reflected color to be predicted from the formulation used to deposit the films. Our work shows that the self-ordering tendency of PNP MGs gives a viable new method for introducing structural color into STPSCs. Because our one-step method for introducing structural color into STPSCs is general, does not introduce any additional processing steps and is scalable whilst also improving device stability, this study may bring deployment of STPSCs closer.

Origin of Sputter Damage during Transparent Conductive Oxide Deposition for Semitransparent Perovskite Solar Cells

Transparent conductive oxides (TCOs) have been widely used as transparent electrodes in numerous optoelectronic devices including perovskite/silicon tandem solar cells. A significant concern regarding the application of TCOs is the...

The buffer – Free semitransparent perovskite solar cells with ion-beam sputtered back electrode

Semitransparent perovskite solar cells (PSCs) have the potential for utilization in tandem photovoltaics (PV) and see-through PV for building integration. The passage of light through the thin-film device structure requires transparent contact at the front and back sides of the device. Typically, transparent contacts are made of wide bang-gap conductive oxides (In2O3:SnO2(ITO), etc.) deposited by magnetron sputtering (MS). The use of conventional MS usually requires the addition of a buffer layer to avoid the damage of the charge transporting layers. In this work, the semitransparent perovskite solar cell with p-i-n architecture is fabricated with ITO back electrode deposited directly on C60 electron transporting layer. A comparative analysis was conducted to evaluate the performance and properties of ITO films deposited using ion-beam sputtering (IBS) and the more common MS method. The IBS process was found to eliminate plasma-substrate interaction, resulting in improved deposition on organic layers. Conversely, the MS method resulted in poor output performance and S-shaped IV characteristics of the semitransparent-PSCs. By utilizing IBS fabrication for the back electrode, the relevant efficiency of 12.65% was achieved for the best device. The changes in chemical, optical, and transport properties of the ITO samples fabricated with different methods were investigated. This study represents the first successful utilization of ion-beam sputtering for the fabrication of semitransparent PSCs.

High-performance and selective semi-transparent perovskite solar cells using 3D-structured FTO

Perovskite solar cells (PSCs) have been in the spotlight as a promising next-generation solar cell. With the tremendous development of power conversion efficiency (PCE) over the past decades, a considerable amount of research has focused on semi-transparent perovskite solar cells for applications. However, the short-circuit current density (JSC) greatly decreases in semi-transparent PSCs with an increase in transmittance, and this results in a significant decrease in PCE. In this study, semi-transparent PSCs were fabricated by controlling the absorption layer thickness and aperture ratio using a 3D-structured FTO manufactured via processes that can work large areas (direct printing and mist-CVD). This strategy has an advantage in that the aperture ratio (transmission/entire area) can be controlled easily by adjusting pattern specification. The effect of a 3D-structured FTO enhanced the diffuse transmittance and shortened the carrier travel distance; further, it minimized the decrease in PCE because of an increase in transmittance. Our fully semi-transparent PSCs (F–PSCs) with the ITO cathode achieved a PCE of 12.0 %–14.6 %, and an average visible transmittance (AVT) of 13.4 %–17.0 %. These results demonstrate that the parameter of semi-transparent PSCs (transmittance and PCE) can be easily tailored to the application by controlling the specification of the pattern.

MXene‐Interconnected Two‐Terminal, Mechanically‐Stacked Perovskite/Silicon Tandem Solar Cell with High Efficiency

AbstractTwo‐terminal, mechanically‐stacked perovskite/silicon tandem solar cells offer a feasible way to achieve power conversion efficiencies (PCEs) of over 35%, provided that the state‐of‐the‐art industrial silicon solar cells and perovskite solar cells (PSCs) are fully compatible with one another. Herein, two‐terminal, mechanically‐stacked perovskite/silicon tandem solar cells are developed by mechanically interconnecting semitransparent PSCs and TOPCon solar cells with a MXene interlayer. The semitransparent PSCs are made from wide‐bandgap perovskite Cs0.15FA0.65MA0.20Pb(I0.80Br0.20)3 films. Furthermore, the co‐additives KPF6 and CH3NH3Cl(MACl) are employed to reduce grain boundaries and intragranular defects in the perovskite, boosting the PCE of the semitransparent PSCs to a record‐high value of 20.96% under reverse scan (RS) through a reduction in non‐radiative recombination probability. These optimized semitransparent PSCs are then employed in MXene‐interconnected two‐terminal, mechanically‐stacked tandem solar cells. The enhanced interfacial carrier transportation, with minimal influence on light transmission, imparted by the MXene flakes allows the tandem solar cells to achieve a stabilized PCE of 29.65%. The tandem cells also exhibit acceptable operational stability and are able to retain ≈93% and 92% of their initial PCEs after 120 min of continuous illumination or storage in ambient air for 1000 h, respectively.

Effects of the Electrical Properties of SnO2 and C60 on the Carrier Transport Characteristics of p-i-n-Structured Semitransparent Perovskite Solar Cells.

Recently, metal halide perovskite-based top cells have shown significant potential for use in inexpensive and high-performance tandem solar cells. In state-of-the-art p-i-n perovskite/Si tandem devices, atomic-layer-deposited SnO2 has been widely used as a buffer layer in the top cells because it enables conformal, pinhole-free, and highly transparent buffer layer formation. In this work, the effects of various electrical properties of SnO2 and C60 layers on the carrier transport characteristics and the performance of the final devices were investigated using a numerical simulation method, which was established based on real experimental data to increase the validity of the model. It was found that the band alignment at the SnO2/C60 interface does, indeed, have a significant impact on the electron transport. In addition, as a general design rule, it was suggested that at first, the conduction band offset (CBO) between C60 and SnO2 should be chosen so as not to be too negative. However, even in a case in which this CBO condition is not met, we would still have the means to improve the electron transport characteristics by increasing the doping density of at least one of the two layers of C60 and/or SnO2, which would enhance the built-in potential across the perovskite layer and the electron extraction at the C60/SnO2 interface.