Semitransparent Organic Solar Cells Research Articles

Minimization of Optical Losses in Colorful Semitransparent Organic Solar Cells Using Antimony Oxide Cavity-Based Fabry-Pérot Etalon Electrodes

Semitransparent organic solar cells (STOSCs) are a technology that combines the benefits of visible light transparency and light-to-electrical energy conversion. One of the greatest opportunities for STOSCs is their integration into windows and skylights in energy-sustainable buildings. For this application, the aesthetic aspects of solar cells may be as important as their electrical performance. Here, our strategy enables to achieve high-quality and colorful STOSCs using Fabry-Pérot etalon-type electrodes. These electrodes are composed of an antimony oxide (Sb2O3) cavity layer and two thin Ag mirrors. These dichroic tri-layer structures perform two functions as top conducting electrodes and color filters. The electrodes are fabricated by thermal evaporation of smooth sheets of Ag and metal oxide thin films, with appropriate thicknesses calculated by the transfer matrix methodology. In this manner, dichroic electrodes with a high spectral purity were achieved with transmission wavelengths that could be accurately tuned throughout the visible spectrum by varying the Sb2O3 cavity thickness. These dual-function electrodes were applied to photovoltaic devices and displayed vivid colors, natural transparency, and good performance as compared to devices that use conventional metal electrodes. Furthermore, to achieve saturated colors and low photocurrent losses, active layer materials were selected such that their transmission peaks matched the transmission maxima of the electrodes. These strategies for colorful STOSCs resulted in power conversion efficiencies (PCEs) of up to 12.1% and maximum transmittances (T MAX) of 22.5% in blue devices, PCEs of up to 9.71% and T MAX of 35.4% in green devices, and PCEs of up to 7.63% and T MAX of 34.7% in red devices.

Practically Viable Approach to Efficient and Reliable Semitransparent Flexible Organic Solar Cells: Face‐Seal Encapsulation Embedded with Tailored Color‐Control Functionality

The success of semitransparent organic solar cells (ST‐OSCs) depends heavily on whether they can achieve high efficiency while meeting the conditions for high transmittance or target apparent color. Herein, a device architecture for ST‐OSCs that achieves both enhanced efficiency and controlled apparent color or high transmittance is proposed, while providing protection from ambient air. In the proposed scheme, cells are encapsulated by a barrier foil embedded with a color‐controlling dielectric mirror (CCDM) structure, which is tailored for selective reflection at the targeted spectral band and transmission in the other spectral band. This approach effectively enhances the photocurrent with little compromise in transmittance, yet it allows control of the color of ST‐OSCs. Preparing these CCDMs independently of cell fabrication, the best material composition is utilized without damaging the underlying layers. With the proposed approach, ST‐OSCs with an efficiency of 8.30% and luminous transmittance over 30.4% are demonstrated. Furthermore, by setting ST‐OSCs in the neutral plane utilizing face‐seal encapsulation geometry, it is shown that these devices can maintain 98% of the initial efficiency even after 2000 cycles of repeated bending at a strain of 0.5%. Moreover, they can maintain initial efficiency very well in a highly damp condition for 120 h.

Interface Modification Enabled by Atomic Layer Deposited Ultra‐Thin Titanium Oxide for High‐Efficiency and Semitransparent Organic Solar Cells

Organic solar cells (OSCs) are considered to have reached a second golden age with profoundly improved power conversion efficiency (PCE) and device stability in recent years. The modification of the interface layer plays a significant role in achieving performance enhancement in OSCs. Herein, the use of the atomic layer deposition (ALD) ultrathin TiOx to modify the interface layer in OSCs is reported. The modification with only two TiOx ALD cycles not only effectively passivates the interface between the ZnO electron transport layer (ETL) and the active layer, but also reduces the series resistance and improves the charge transport process in the device. An absolute 1% increase in PCE with enhanced device stability for modified OSCs is achieved. Semitransparent OSCs are also fabricated by applying this interface modification strategy. The modification with two TiOx ALD cycles increases the electrical device performance without affecting the optical properties of the semitransparent device. An average PCE of 10.46% with an average visible transmittance (AVT) of 19.61% and a color rendering index (CRI) close to 100 is demonstrated for the fabricated semitransparent device with the modification. The ALD‐assisted interface modification provides a straightforward way to realize high‐performance semitransparent OSCs.

Large area semitransparent inverted organic solar cells with enhanced operational stability using TiO2 electron transport layer for building integrated photovoltaic devices

Herein, we have demonstrated the semitransparent organic solar cell (OSC) devices in inverted architecture with TiO2 as an electron transport layer (ETL). A comparative study is performed with widely used ZnO ETL based devices. The devices with TiO2 ETL exhibits better device efficiency (2.44%) in comparison to ZnO counterparts (1.94%). The transfer matrix calculations finding indeed validate the experimental results. Furthermore, the large area OSC devices of size 1 cm2 have been fabricated. The device stability is investigated under operational conditions by measuring time dependent device performance in biased condition at maximum power point. Our findings suggest that the devices fabricated using TiO2 ETL is much more durable as compare to ZnO based devices.

A critical review on semitransparent organic solar cells

Semitransparent solar cells not only can generate electricity but also exhibit promising application in facades and roofs of building, as well as the coatings of vehicle. Ideal semitransparent solar cells should have a high utilization efficiency of ultraviolet and near infrared photons, and maintain an appropriate balance between absorption and transparency in visible light range. Organic semiconducting materials with adjustable optical band gap own great potential in preparing highly efficient semitransparent organic solar cells (OSCs). There are great challenges in achieving semitransparent electrodes with good conductivity and high transmittance in visible light range, as well as high reflectance in ultraviolet and near infrared range. In this critical review, we summarize the recent progress of semitransparent OSCs, concentrating on organic semiconducting materials, semitransparent top electrode and device engineering. Semitransparent OSCs have attracted more and more attention due to its great potential in energy source in door, electricity-generating windows, building-integrated photovoltaics and agricultural greenhouse. Semitransparent OSCs have attracted more and more attention due to its great potential in electricity-generating windows, building-integrated photovoltaics and agricultural greenhouse. This review comprehensively summarizes recent progresses of organic material, semitransparent top electrode and device engineering, the challenges on achieving semitransparent OSCs are highlighted to promote the development of this field. • Recent development of organic materials with strong ultraviolet or near infrared absorption were summarized. • The key parameters for evaluating the performance of semitransparent OSCs were discussed. • This review comprehensively summarized recent progress of transparent top electrodes. • The light management methods and device designs are firstly comprehensively reported.

Optimising Non-Patterned MoO3/Ag/MoO3 Anode for High-Performance Semi-Transparent Organic Solar Cells towards Window Applications.

Semi-transparent organic solar cells (ST-OSCs) have attracted significant research attention, as they have strong potential to be applied in automobiles and buildings. For ST-OSCs, the transparent top electrode is an indispensable component, where the dielectric/metal/dielectric (D/M/D) structured electrode displayed a promising future due to its simplicity in the fabrication. In this work, by using the MoO3-/Ag-/MoO3-based D/M/D transparent electrode, we fabricated ST-OSCs based on the PM6:N3 active layer for the first time. In the device fabrication, the D/M/D transparent electrode was optimised by varying the thickness of the outer MoO3 layer. As a result, we found that increasing the thickness of the outer MoO3 layer can increase the average visible transmittance (AVT) but decrease the power conversion efficiency (PCE) of the device. The outer MoO3 layer with a 10 nm thickness was found as the optimum case, where its corresponding device showed the PCE of 9.18% with a high AVT of 28.94%. Moreover, the colour perception of fabricated ST-OSCs was investigated. All semi-transparent devices exhibited a neutral colour perception with a high colour rendering index (CRI) over 90, showing great potential for the window application.

Aesthetic and colorful: Dichroic polymer solar cells using high-performance Fabry-Pérot etalon electrodes with a unique Sb2O3 cavity

Abstract Semitransparent organic solar cells (STOSCs) are a technology that combines the benefits of visible light transparency and light-to-electrical energy conversion. One of the greatest opportunities for STOSCs is their integration into windows and skylights in energy-sustainable buildings. For this application, the aesthetic aspects of solar cells may be as important as their electrical performance. Here, our strategy enables to achieve high-quality and colorful STOSCs using Fabry-Perot etalon-type electrodes. These electrodes are composed of an antimony oxide (Sb2O3) cavity layer and two thin Ag mirrors. These dichroic tri-layer structures perform two functions as top conducting electrodes and color filters. These dual-function electrodes were applied to photovoltaic devices and displayed vivid colors, natural transparency, and good performance as compared to devices that use conventional metal electrodes. Furthermore, to achieve saturated colors and low photocurrent losses, active layer materials were selected such that their transmittance peaks matched the transmittance maxima of the electrodes. These strategies for colorful STOSCs result in power conversion efficiencies (PCEs) of up to 13.3% and maximum transmittances (TMAX) of 24.6% in blue devices, PCEs of up to 9.71% and TMAX of 35.4% in green devices, and PCEs of up to 7.63% and TMAX of 34.7% in red devices.

Water-assisted formation of highly conductive silver nanowire electrode for all solution-processed semi-transparent perovskite and organic solar cells

Transparent conductive electrode (TCE) is an essential part of modern optoelectronic devices. Silver nanowire (AgNW) is regarded as the most promising TCEs, owing to its balanced conductivity and transparency, and solution processability. The use of insulating polyvinyl pyrrolidone (PVP) surfactant limits the conductivity of the final AgNW networks. Herein, by introducing a small amount of deionized water into the AgNWs dispersion in isopropanol (IPA), the conductivity of the spray-coated AgNW electrode was significantly improved. Sheet resistance (Rs) of 27.0 Ω □−1 with transparency of 92% (at 550 nm) was obtained for the AgNW films spray coated from the AgNW ink with 20% water, which is much lower than the IPA-only AgNW film (120.9 Ω □−1 with similar transparency). Morphology analysis confirmed that water is able to wash PVP away from the AgNW surface and promote the formation of AgNW bundles, which increase the conductivity. The optimized AgNW ink was then used for perovskite and polymer solar cells. High power conversion efficiencies of 14.04% for perovskite solar cell and 6.44% for organic solar cells with averaged light transmittance of 21.7% and 33.12% are achieved, respectively, which are among the highest values for all solution-processed semi-transparent perovskite and polymer solar cells.

High-Performance Semitransparent Organic Solar Cells with Excellent Infrared Reflection and See-Through Functions.

Clean energy production and saving play vital impacts on the sustainability of the global community. Herein, high-performance semitransparent organic solar cells (ST-OSCs) with excellent features of power generation, being see-through, and infrared reflection of heat dissipation, with promising perspectives for building-integrated photovoltaics (BIPVs) are reported. To simultaneously improve average visible transmittance (AVT) and power conversion efficiency (PCE), formally in a trade-off relationship, of ST-OSCs, new ternary blends with alloy-like near-infrared (NIR) acceptors are employed, which are effective to improve device efficiency while maintaining visible absorption unchanged, resulting in PCEs of 16.8% for opaque devices and 13.1% for semitransparent OSCs (AVT of 22.4% and infrared photon radiation rejection (IRR) of 77%). Further, multifunctional ST-OSCs are realized via introducing simple, yet effective photonic reflectors, together with optical simulation, leading to not only perfect fitting of the visible transmittance peak (555nm) to the photopic response of the human eye but also an excellent IRR of 90% (780-2500nm), along with 23% AVT and over 12% PCE. This is thought to be the best-performing multifunctional ST-OSC with promising prospects as BIPVs in terms of power generation, heat dissipation, and being see-through.

Semitransparent Flexible Organic Solar Cells

Abstract The semitransparent flexible organic solar cell takes advantages of flexibility, transparency, color adjustment property, which is more conducive to integrate on buildings and mobile terminals. Ascribing to the developments of narrow band gap donors and the new non-fullerene acceptors, the power conversion efficiency of semitransparent flexible organic solar cells has been achieved 10% to 12% with average visible transmittance of 17% to 21%. This review summarizes the molecular design of the most representative active layer materials, and discusses the characterization of semitransparent parameters paradigms, then we discuss how to optimize the device in combination with optical simulation, and finally list the recent development of semitransparent flexible electrodes of ITO-free organic solar cells, and give our perspectives on the next step direction.

Fibril Network Strategy Enables High‐Performance Semitransparent Organic Solar Cells

AbstractThe development of semitransparent organic solar cells (ST‐OSCs) represents a significant step toward the commercialization of OSCs. However, the trade‐off between power conversion efficiency (PCE) and average visible transmittance (AVT) restricts further improvements of ST‐OSCs. Herein, it is demonstrated that a fibril network strategy can enable ST‐OSCs with a high PCE and AVT simultaneously. A wide‐bandgap polymer PBT1‐C‐2Cl that can self‐assemble into a fibril nanostructure is used as the donor and a near‐infrared small molecule Y6 is adopted as the acceptor. It is found that a tiny amount of PBT1‐C‐2Cl in the blend can form a high speed pathway for hole transport due to the well distributed fibril nanostructure, which increases the transmittance in the visible region. Meanwhile, the acceptor Y6 guarantees sufficient light absorption. Using this strategy, the optimized ST‐OSCs yield a high PCE of 9.1% with an AVT of over 40% and significant light utilization efficiency of 3.65% at donor/acceptor ratio of 0.25:1. This work demonstrates a simple and effective approach to realizing high PCE and AVT of ST‐OSCs simultaneously.

Spin-coated 10.46% and blade-coated 9.52% of ternary semitransparent organic solar cells with 26.56% average visible transmittance

Semitransparent organic solar cells (ST-OSCs) have drawn great attention due to their wide application, such as smart windows, greenhouses and building integrated photovoltaics. The ternary strategy is often considered an useful way to enhance device performance due to improve the attracting or retracting morphology. Here, non-fullerene small molecule (Y8) with electron-deficient core as the center unit and a novel PBDTTT-type low-bandgap polymer (PCE10) were chosen to fabricate ST-OSCs according to the principle of more closely matched energy levels. With the introduction of indene-C60bisadduct (ICBA) as third component, opaque organic solar cells with a power conversion efficiency (PCE) of 12.86% and ST-OSCs with a PCE of 10.46% were obtained by using spin coating after optimization. The average visible transmittance of ST-OSCs is up to 26.56%. By the blade coating technique, 9.52% PCE is achieved for ST-OSCs, which is the highest value reported to date. These results show that it's higher efficiency to improve the performance of ST-OSCs through ternary strategy. And the blade coating technique has a promising application prospect for mass manufacturing ST-OSCs.

Narrow Bandpass and Efficient Semitransparent Organic Solar Cells Based on Bioinspired Spectrally Selective Electrodes.

The visual aesthetic that involves color, brightness, and glossiness is of great importance for building integrated photovoltaics. Semitransparent organic solar cells (ST-OSCs) are thus considered as the most promising candidate due to their superiority in transparency and efficiency. However, the realization of high color purity with narrow bandpass transmitted light usually causes the severely suppressed transparency in ST-OSCs. Herein, we present a spectrally selective electrode (SSE) by imitating the integrating strategy of beetle cuticle for achieving narrow bandpass ST-OSCs with high efficiency and long-term stability. The proposed SSE allows for efficient light-selective passage, leading to tunable narrow bandpass transmitted light from violet to red. An optimized power conversion efficiency of 15.07% is achieved for colorful ST-OSCs, which exhibit color purity close to 100% and a peak transmittance approaching 30%. Long-term stability is also improved for ST-OSCs made with this SSE due to the light-rejecting and the moisture-blocking abilities. The realization of bright and colorful ST-OSCs also indicates the application potential of SSEs in light-emitting diodes, lasers, and photodetectors.

Semitransparent Organic Solar Cells Enabled by a Sequentially Deposited Bilayer Structure.

Semitransparent organic solar cells (ST-OSCs) have been regarded as a promising candidate for building integrated photovoltaics. In general, most of the ST-OSCs are based on a bulk heterojunction (BHJ) structure in which the morphology of the BHJ film must be delicately optimized. In this work, we introduce a sequentially deposited bilayer structure into ST-OSCs by using a PTB7-Th/IEICO-4F combination. The adoption of the bilayer structure not only simplifies the device optimization, but it is also found that, as the donor and the acceptor are separately deposited, the power conversion efficiency (PCE) of bilayer ST-OSCs can be improved by simply increasing the thickness of IEICO-4F, which has strong near infrared absorption but weak visible light absorption, without significantly affecting the average visible light transmittance (AVT) of the device. However, in the BHJ structure, the increase in BHJ film thickness unavoidably enhances the donor absorption in the visible light region, leading to a tradeoff between the PCE and AVT in BHJ-structured ST-OSCs. Eventually, the bilayer-structured device exhibits a better overall performance than the BHJ-structured device, e.g., a PCE of 8.5% for the bilayer structure versus a PCE of 8.1% for the BHJ structure with an AVT around 21%. Our findings indicate that the sequentially deposited bilayer structure, aside from its easy processing characteristics, also has great potential for preparing high-performance ST-OSCs.

Achieving Net Zero Energy Greenhouses by Integrating Semitransparent Organic Solar Cells

Summary Greenhouses vastly increase agricultural land-use efficiency. However, they also consume significantly more energy than conventional farming due in part to conditioning the greenhouse space. One way to mitigate the increase in energy consumption is to integrate solar modules onto the greenhouse structure. Semitransparent organic solar cells (OSCs) are particularly attractive given that their spectral absorption can be tuned to minimize the attenuation of sunlight over the plants photosynthetically active spectrum. Here, the benefits of integrating OSCs on the net energy demand of greenhouses within the U.S. are determined through a detailed energy balance model. We find that these systems can have an annual surplus of energy in warm and moderate climates. Furthermore, we show that sunlight reduction entering the greenhouse can be minimized with appropriate design. These results demonstrate that OSCs are an excellent candidate for implementing in greenhouses and provide an opportunity to diversify sustainable energy generation technology.

Film-depth-dependent crystallinity for light transmission and charge transport in semitransparent organic solar cells

We realized simultaneously optimized optical and electronic properties in semitransparent organic solar cells by tuning the film-depth-dependent crystallinity distribution.

Material perceptions and advances in molecular heteroacenes for organic solar cells

This review showcases the development of heteroacene-based molecular materials and their role in high performance binary, ternary, tandem and semitransparent organic solar cells.

Semitransparent Organic Solar Cells based on Non-Fullerene Electron Acceptors

Semitransparent Organic Solar Cells based on Non-Fullerene Electron Acceptors

Improving the charge transport of the ternary blend active layer for efficient semitransparent organic solar cells

With the aid of a suitable third component acceptor material, the best-performance semitransparent organic solar cell shows an outstanding efficiency of 13.49% at an average visible transmittance of 22.58%.

Retarding Ion Exchange between Conducting Polymers and Ionic Liquids for Printable Top Electrodes in Semitransparent Organic Solar Cells.

Semitransparent organic solar cells (ST-OSCs) are considered to be an influential tool for aesthetic and economic building-integrated photovoltaics, which can be fabricated by the printing technology. A poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) and ionic liquid (IL) composite has been considered as an electrode for ST-OSCs because of its high electrical conductivity, high transparency, and printability. However, we found that the introduction of IL into the PEDOT:PSS solution for enhancing its electrical conductivity results in (1) nonreliable printing of PEDOT:PSS/IL composite films because of gradual gelation of the mixture solution and (2) the production of chemically reactive ion pairs during ion exchange between PSS and IL, which induces the oxidation of the underlying organic semiconductors during printing. To solve these problems, we developed a sequential printing method using pristine PEDOT:PSS and IL solutions to retard ion exchange, thus preventing chemical doping of organic semiconductors by newly generated ion pairs. Finally, by using only solution processes, we demonstrate efficient ST-OSCs with a printed PEDOT:PSS/IL composite as the top electrode, exhibiting a power conversion efficiency of 6.32% at an average visible transmittance of 35.4%.