Perovskite Photovoltaic Cells Research Articles

Perovskite PV-Powered RFID: Enabling Low-Cost Self-Powered IoT Sensors

Photovoltaic (PV) cells have the potential to serve as on-board power sources for low-power IoT devices. Here, we explore the use of perovskite solar cells to power Radio Frequency (RF) backscatter-based IoT devices with a few {\mu}W power demand. Perovskites are suitable for low-cost, high-performance, low-temperature processing, and flexible light energy harvesting that hold the possibility to significantly extend the range and lifetime of current backscatter techniques such as Radio Frequency Identification (RFID). For these reasons, perovskite solar cells are prominent candidates for future low-power wireless applications. We report on realizing a functional perovskite-powered wireless temperature sensor with 4 m communication range. We use a 10.1% efficient perovskite PV module generating an output voltage of 4.3 V with an active area of 1.06 cm2 under 1 sun illumination, with AM 1.5G spectrum, to power a commercial off-the-shelf RFID IC, requiring 10 - 45 {\mu}W of power. Having an on-board energy harvester provides extra-energy to boost the range of the sensor (5x) in addition to providing energy to carry out high-volume sensor measurements (hundreds of measurements per min). Our evaluation of the prototype suggests that perovskite photovoltaic cells are able to meet the energy needs to enable fully autonomous low-power RF backscatter applications of the future. We conclude with an outlook into a range of applications that we envision to leverage the synergies offered by combining perovskite photovoltaics and RFID.

Self‐Powered Sensors Enabled by Wide‐Bandgap Perovskite Indoor Photovoltaic Cells

AbstractA new approach to ubiquitous sensing for indoor applications is presented, using low‐cost indoor perovskite photovoltaic cells as external power sources for backscatter sensors. Wide‐bandgap perovskite photovoltaic cells for indoor light energy harvesting are presented with the 1.63 and 1.84 eV devices that demonstrate efficiencies of 21% and 18.5%, respectively, under indoor compact fluorescent lighting, with a champion open‐circuit voltage of 0.95 V in a 1.84 eV cell under a light intensity of 0.16 mW cm−2. Subsequently, a wireless temperature sensor self‐powered by a perovskite indoor light‐harvesting module is demonstrated. Three perovskite photovoltaic cells are connected in series to create a module that produces 14.5 µW output power under 0.16 mW cm−2 of compact fluorescent illumination with an efficiency of 13.2%. This module is used as an external power source for a battery‐assisted radio‐frequency identification temperature sensor and demonstrates a read range by of 5.1 m while maintaining very high frequency measurements every 1.24 s. The combined indoor perovskite photovoltaic modules and backscatter radio‐frequency sensors are further discussed as a route to ubiquitous sensing in buildings given their potential to be manufactured in an integrated manner at very low cost, their lack of a need for battery replacement, and the high frequency data collection possible.

Halide Perovskite Solar Cell Efficiency Improvements: New Device Type Simulation

Trihalide perovskite photovoltaic (P-PV) solar cells have a promise to be connected into tandems with inorganic PV systems. In this paper, we present p-i-n GaAs & P-PV cells in either in a series way or parallel connection. Comparisons made for two types of tandems by a non-monolithic connection of two experimental sub-cells and results are being discussed based on simulation analysis. It is shown that the parallel connection is always preferable when the sub-cells photocurrent is not balanced while Voc (open circuit voltage) is close to each other. Total efficiency over 20% is demonstrated for GaAs shading effect by MAPbI3 (methylammonium lead halide) film, with achieved Jsc - 41 mA/cm2 (short circuit current density) and high Voc

Perovskite Photovoltaic Cell with Hole Transport Layer Based on a Polyaniline Complex

Perovskite solar cells with photoactive layer of methylammonium lead iodide and hole transport layer based on a polyaniline complex with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) have been developed for the first time. The power conversion efficiency of obtained cells is comparable with that of known analogs. Results of simulation of the optical parameters of cells in the framework of the Maxwell–Garnet model showed that the experimentally observed weak dependence of the power conversion efficiency on the perovskite layer thickness within 350–500 nm is related to the absence of significant variation of both the energy absorbed by the photoactive layer and the exciton generation rate.

High-Performance Large-Area Luminescence Solar Concentrator Incorporating a Donor–Emitter Fluorophore System

A high-performance large-area luminescent solar concentrator (LSC) is demonstrated, fabricated via careful choice of the fluorophore system, waveguide material, and coupled photovoltaic (PV) cells. Doctor-blading was used to deposit a PMMA–dye blend film on the surface of a PMMA planar waveguide to fabricate the large-area LSC with dimensions of 20 × 20 × 0.1 cm3. A perylene diimide-based donor–emitter fluorophore pair was chosen to both improve the photoluminescent quantum yield and reduce the luminescence reabsorption. Three types of photovoltaic cells were coupled to the LSC to optimize the device output performance. With the combination of the donor–emitter fluorophore pair chosen, the PMMA-based LSC deposition process and coupled perovskite PV cells, the LSC has an experimental flux gain of 7.4 at a geometric gain of 50 (G = 50) under 1 sun irradiation, with a power conversion efficiency of 2.6%.

Integrated advantages from perovskite photovoltaic cell and 2D MoTe2 transistor towards self-power energy harvesting and photosensing

Perovskite photovoltaic (PV) cell researches have been extensively conducted due to its unprecedentedly excellent power conversion efficiencies (PCEs), which are reported to be over 23.7% in maximum. Despite the high PCEs, there are several unresolved issues on optimal interface states in the cell and device stabilities. Moreover, beyond the simple PV device issues, extended device or circuit applications have rarely been reported although it seems equally important to fully reveal the self-power energy harvesting functions of the perovskite cells to modern ubiquitous environment. Here, we integrate a realistic self-power circuit utilizing a few nm-thin molybdenum ditelluride (MoTe2) field effect transistors (FETs) as well as perovskite PV cells. The PV cells intrinsically show more than 0.9 V of open circuit voltage (VOC) under artificial sun (AM 1.5) or visible photon illumination, so we thus used a red-light emitting diode (LED) to simply generate ~1 V of photovoltage. Two modes for practical operation were consequently observed from the circuit, depending on the light intensity: self-power current/voltage source mode (high intensity) and photosensor mode (low intensity). We now conclude that our self-power circuit approaches integrating perovskite cells and 2D MoTe2 FET could attract much attention for future ubiquitous electronics and energy harvest applications.

Enhanced Charge Transport via Metallic 1T Phase Transition Metal Dichalcogenides‐Mediated Hole Transport Layer Engineering for Perovskite Solar Cells

AbstractIn perovskite photovoltaic cells having a p‐i‐n structure, the hole transport layer (HTL) plays an important role in device performance because it has a direct impact on the crystallinity of overlying perovskite films as well as the interfacial charge transport. Poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT : PSS) has been widely used as an HTL owing to its desirable electrical and optical properties with solution processability. However, improving the functionality of PEDOT : PSS still requires broad attention to maximize the related solar cell performance, such as further enhancing the electrical properties to achieve better charge transport at the electrode and photoactive layer interface and reducing the nucleation energy barrier to improve crystallinity of the overlying perovskite films. Two‐dimensional transition metal dichalcogenides (TMDs) have been studied in various optoelectronic devices owing to their intriguing optoelectric features. In this study, tungsten diselenide (WSe2) was implemented with PEDOT : PSS to enhance the performance in p‐i‐n perovskite solar cells. The incorporation of WSe2 into PEDOT : PSS led to improved charge transport at the photoactive layer and electrode interface as well as the favorable growth of the perovskite crystal. As a result, a notable improvement in the performance of the solar cell having the WSe2‐mediated PEDOT : PSS HTL was observed in comparison to that of the PEDOT : PSS only device, which had power conversion efficiencies of 16.3% and 13.8%, respectively. The facile approach proposed in this study may be readily extended to various other perovskite‐based optoelectronic devices beyond solar cells toward the enhancement of device functionality.

Reducing Surface Recombination Velocities at the Electrical Contacts Will Improve Perovskite Photovoltaics

We explore the effects of nonradiative recombination at the extracting contacts on the achievable performance of halide perovskite photovoltaic cells. First, we perform device simulations using standard drift-diffusion models with experimental semiconductor parameters matching those of methylammonium lead triiodide (MAPbI3). We quantify the range of surface recombination velocities (SRVs) that would allow this archetypal perovskite to reach power conversion efficiencies of 27%. In particular, for contacts with well-aligned energy levels, SRVs of ∼1–10 cm/s should enable open-circuit voltages of 1.30 V, within 96% of the Shockley–Queisser limit. Next, we use time-resolved photoluminescence to experimentally determine the SRVs on 14 different common electron- and hole-extracting contacts, including TiO2, SnO2, ZnO, PCBM, ITIC, ICBA, TPBi, PEDOT:PSS, PTAA, PVK, NiO, MoO3, WO3, and spiro-OMeTAD. These results point the way to the selection and rational engineering of better contacts as a means to achieve high...

Thiourea Interfacial Modification for Highly Efficient Planar Perovskite Solar Cells

Interfacial engineering is an efficient strategy for enhancing the performance of perovskite photovoltaic cells. Here, we present a novel method to modify the surface of TiO2 with thiourea. X-ray photoelectron spectroscopy indicates that thiourea treatment inactivates the TiO2 surface groups. Kelvin probe force microscopy and ultraviolet photoelectron spectra demonstrate an energy level downshift of the modified TiO2. Photoluminescence spectra reveal the reduced interface charge recombination and an improved charge transportation/extraction. Tafel and Nyquist plots elucidate a decrease of trap-state density and an increase of conductivity of the modified TiO2. Hence, the planar perovskite solar cell based on the TiO2 electron transport layer (ETL) modified with 0.1 M thiourea yields an efficiency of 19.18%, which is 7.5% larger than that of the device based on the pristine TiO2 ETL. The simple procedure and the significant performance improvement render this method promising.

Outstanding Indoor Performance of Perovskite Photovoltaic Cells – Effect of Device Architectures and Interlayers

Indoor photovoltaics is one of the best sustainable and reliable energy source for low power consumption electronics such as the rapidly growing Internet of Things. Perovskite photovoltaic (PPV) cells with three benchmark device architectures – mesoporous PPV (mPPV) and inverted PPV (iPPV) with alternative hole transporting layers (HTLs), and carbon‐based PPV (cPPV) are studied under a simulated indoor environment. The mPPV cell using typical Spiro‐OMeTAD as the HTL shows the highest maximum power density (Pmax) of 19.9 μW cm−2 under 200 lux and 115.6 μW cm−2 under 1000 lux (without masking), which is among the best of the indoor PV. Interestingly, when PTAA is used as the HTL in the mPPV cell, the Pmax drops to almost zero under indoor light environment while its performance under one sun remains similar. On the other hand, when PEDOT:PSS is replaced by Poly‐TPD as HTL in the iPPV cell, the Pmax under indoor light improves significantly and is comparable to that of the best mPPV cell. This significant difference in indoor performance correlates well with their leakage current. The HTL‐free cPPV cell, prepared by fully up‐scalable techniques, shows a promising Pmax of 16.3 and 89.4 μW cm−2 under 200 and 1000 lux, respectively. A practical scale 5 × 5cm2 cPPV module is fabricated as a demonstration for real applications.

Enhanced interface of polyurethane acrylate via perfluoropolyether for efficient transfer printing and stable operation of PEDOT:PSS in perovskite photovoltaic cells

In this study, the efficient transfer printing and stable operation of the PEDOT:PSS hole extraction layer have been researched in the perovskite solar cell, in terms of the development from an enhanced hydrophobic interface of polyurethane acrylate (PUA) mold film via perfluoropolyether. First, the energy release rate of the mold film is controlled successfully for an efficient transfer process, which was confirmed by contact angle measurements compared to the normal PUA. The transfer-printed PEDOT:PSS layer exhibits comparable smoothness, and also induces the favorable crystallinity of perovskite related to the spin-coated layer, which shows similar JSC and PCE (spin-coated compared to transfer printing: 12.85% compared to 12.33%), and improved VOC. The effects of the device electrical parameters are analyzed in detail by PL mapping, charge carrier mobility, and impedance response. Furthermore, the stability of the device with transfer-printed PEDOT:PSS achieved 90% retention for approximately 40 days, which was affected by the preserved crystallinity of perovskite, and the inhibition of the degradation of ITO from XRD and XPS analyses, respectively. Consequently, the transfer-printed hole extraction layer through the interface control between PUA and PEDOT:PSS using the improved hydrophobicity contributes to maintaining the surface morphologies and device electrical properties; this correlates with the stable operation of perovskite photovoltaics.

Perovskite photovoltaic cells with ultra-thin buffer layers for tandem applications

Perovskite photovoltaic cells (PVs) and their tandem application with silicon PVs are strong candidates for low-cost energy harvesting device. To utilize efficient perovskite-based tandem devices, parasitic absorption from buffer layers should be minimized. Here, we demonstrated an infrared (IR)-transparent perovskite PV employing ultra-thin buffer layers. Since vacuum-deposited layers follow underlying structure, thermally evaporated thin buffer layer (<15 nm) successfully covers perovskite film. These thin buffer layers provide selective carrier transport to the electrode because of their high energy barrier (>1 eV) compared to active layer. Moreover, as a result of reduced parasitic absorption, the transmittance of device with thin buffer layers is over 80% at near IR region (800–1100 nm), which allows low energy photons to penetrate top cell of tandem device. The engineering of a top perovskite PV and stacking it with commercialized silicon PVs lead to 19.4% (four-terminal) efficient tandem devices.

Scalable Triple Cation Mixed Halide Perovskite–BiVO4 Tandems for Bias‐Free Water Splitting

AbstractStrong interest exists in the development of organic–inorganic lead halide perovskite photovoltaics and of photoelectrochemical (PEC) tandem absorber systems for solar fuel production. However, their scalability and durability have long been limiting factors. In this work, it is revealed how both fields can be seamlessly merged together, to obtain scalable, bias‐free solar water splitting tandem devices. For this purpose, state‐of‐the‐art cesium formamidinium methylammonium (CsFAMA) triple cation mixed halide perovskite photovoltaic cells with a nickel oxide (NiOx) hole transport layer are employed to produce Field's metal‐epoxy encapsulated photocathodes. Their stability (up to 7 h), photocurrent density (–12.1 ± 0.3 mA cm−2 at 0 V versus reversible hydrogen electrode, RHE), and reproducibility enable a matching combination with robust BiVO4 photoanodes, resulting in 0.25 cm2 PEC tandems with an excellent stability of up to 20 h and a bias‐free solar‐to‐hydrogen efficiency of 0.35 ± 0.14%. The high reliability of the fabrication procedures allows scaling of the devices up to 10 cm2, with a slight decrease in bias‐free photocurrent density from 0.39 ± 0.15 to 0.23 ± 0.10 mA cm−2 due to an increasing series resistance. To characterize these devices, a versatile 3D‐printed PEC cell is also developed.

Mixed-halide Pb-Sn binary perovskite films with various Sn-content for Pb-reduced solar cells

We proposed and examined a material group of methylammonium Pb-Sn mixed halide (MAPb1−xSnxI2.6Br0.4) with various Sn-content (x = 0.2–0.8) for Pb-reduced perovskite solar cells. With suitable Pb-Sn ratio (x = 0.4–0.6), dense coverage of films with better crystallinity was obtained compared with low Sn ratio (x = 0.2). For excess Sn ratio (x = 0.8), poor film-uniformity was found in spite of its enhanced crystallinity. Optimum composition (x = 0.6) provided an impressive power conversion efficiency of 13.4% with remarkable photocurrent output stability, which is related to suppression of trap-assisted recombination regarding the perovskite materials. This promising material paves the way for development of highly efficient, Pb-reduced perovskite photovoltaic cells.

Alignment of Cascaded Band-Gap via PCBM/ZnO Hybrid Interlayers for Efficient Perovskite Photovoltaic Cells

In this study, we investigated methylammonium lead iodide (MAPbI3)-perovskite solar cells (PSCs) with hybrid PC70BM/ZnO interlayers. The pristine device which had a PC70BM electron transport layer sandwiched between ITO/PEDOT:PSS/MAPbI3 and TiO x /Al electrodes exhibited PCE of 12.72% with a V OC of 0.98 V, J sc of 18.41 mA/cm2, and FF of 71%. The new device with hybrid PC70BM/ZnO interlayers exhibited higher PCE of 14.17% with a V OC of 0.98 V, J SC of 20.08 mA/cm2, and FF of 72% due to the incorporation of ZnO nanoparticles in PC70BM electron transport layer (ETL) with high electron mobility and cascade band gap alignment. Here, we demonstrated that lower photoluminescence (PL) intensity of the device with hybrid interlayers could improve the JSC value of perovskite solar cells due to enhanced charge-generation efficiency. Contact resistance can be reduced by mixing ZnO nanoparticles with PC70BM electron transport layer without additional ZnO layer insertion.

Highly efficient and stable semi-transparent perovskite solar modules with a trilayer anode electrode.

Highly efficient and stable semi-transparent CH3NH3PbI3 perovskite photovoltaic cells are realized by using an ITO/MoOx bilayer conductive oxide as the anode electrode with a cyclopenta[2,1-b;3,4-b']dithiophene (CT) based hole-transport material (HTM), which allows bifacial illumination from both sides of the electrodes. The wide bandgap MoOx thin film is not only to be an electron blocking layer, but also to be a passivation layer which can withstand the excessive energy bombardment during the magnetron sputtering process for the deposition of a high-quality ITO thin film. Atomic-force microscopy images, transmittance spectra and water-droplet contact angle images show that the interfacial contact between MoOx and hole transport layer (HTL) strongly influences the short-circuit current density (JSC) and fill factor (FF). The highest power conversion efficiency (PCE) values for the bifacial perovskite solar cells (0.16 cm2) and modules (11.7 cm2) are 16.38% and 14.96%, respectively. In addition, the PCE of the ITO/MoOx/CT-HTM based perovskite solar module decreases slowly toward a stable value (∼11%) for more than 700 h under wet environment conditions (70 ± 5 RH%).

Roll to roll atmospheric pressure plasma enhanced CVD of titania as a step towards the realisation of large area perovskite solar cell technology

Highly effective TiO2−x electron transport layers produced by continuous atmospheric pressure PECVD achieve efficiency gains in mesoporous perovskite photovoltaic cells.

Influence of Moisture on Perovskite Photovoltaic Cells

This paper deals with the influence of moisture on perovskite photovoltaic cells. Moisture is considered to be one of the most common degradation mechanisms. However, research has found that the use of 20% relative humidity (RH) enviroment in the production of perovskite solar cells has a positive effect on its conversion efficiency. Perovskite active layer with moisture impact had also a less continuous morphology and film formation was faster. The perovskite grains have unified leading to the enlargement of its volume. This reduced the number of grain boundaries (barrier to the generated current). The conversion efficiency of the perovskite photovoltaic cells produced at 20% RH was η = 7 %. The conversion efficiency of the perovskite cells in environment without humidity has reached approximately η = 5 %.

Manufacturing cost and market potential analysis of demonstrated roll-to-roll perovskite photovoltaic cell processes

Perovskite photovoltaic solar cells and modules can be manufactured using roll-to-roll (R2R) techniques, which have the potential for very low cost production. Understanding cost barriers and drivers that will impact its future commercial viability can beneficially guide research directions. Because processes, materials and equipment for manufacturing are still under development, it is difficult to estimate these costs accurately. We use a cost method developed to allow for uncertainty in the input assumptions to analyse three demonstrated R2R compatible manufacturing sequences and two potential optimised sequences. Using these novel methods, we have identified and quantified key cost barriers; high cost materials P3HT and PCBM, the use of evaporation for the rear metal deposition, and the transparent ITO coating. We project that technology developments in these key areas would halve the expected manufacturing cost to US$37/m±30%. With 68% GFF, 10% PCE and a 3 year lifetime, such R2R perovskite modules would be competitive with existing flexible PV products in the market on a $/W and power to weight basis. To compete with Si and CdTe in the flat plate PV market, PCE and lifetimes in excess of 15% and 15 years respectively would be required.

Incoherent population mixing contributions to phase-modulation two-dimensional coherent excitation spectra.

We present theoretical and experimental results showing the effects of incoherent population mixing on two-dimensional (2D) coherent excitation spectra that are measured via a time-integrated population and phase-sensitive detection. The technique uses four collinear ultrashort pulses and phase modulation to acquire two-dimensional spectra by isolating specific nonlinear contributions to the photoluminescence or photocurrent excitation signal. We demonstrate that an incoherent contribution to the measured line shape, arising from nonlinear population dynamics over the entire photoexcitation lifetime, generates a similar line shape to the expected 2D coherent spectra in condensed-phase systems. In those systems, photoexcitations are mobile such that inter-particle interactions are important on any time scale, including those long compared with the 2D coherent experiment. Measurements on a semicrystalline polymeric semiconductor film at low temperatures show that, in some conditions in which multi-exciton interactions are suppressed, the technique predominantly detects coherent signals and can be used, in our example, to extract homogeneous line widths. The same method used on a lead-halide perovskite photovoltaic cell shows that incoherent population mixing of mobile photocarriers can dominate the measured signal since carrier-carrier bimolecular scattering is active even at low excitation densities, which hides the coherent contribution to the spectral line shape. In this example, the intensity dependence of the signal matches the theoretical predictions over more than two orders of magnitude, confirming the incoherent nature of the signal. While these effects are typically not significant in dilute solution environments, we demonstrate the necessity to characterize, in condensed-phase materials systems, the extent of nonlinear population dynamics of photoexcitations (excitons, charge carriers, etc.) in the execution of this powerful population-detected coherent spectroscopy technique.