Semitransparent Organic Solar Cells Research Articles

18.01% Efficiency organic solar cell and 2.53% light utilization efficiency semitransparent organic solar cell enabled by optimizing PM6:Y6 active layer morphology

18.01% Efficiency organic solar cell and 2.53% light utilization efficiency semitransparent organic solar cell enabled by optimizing PM6:Y6 active layer morphology

High‐Efficiency Microcavity Semitransparent Organic Photovoltaics with Simultaneously Improved Average Visible Transmittance and Color Rendering Index

Semitransparent organic solar cells (ST‐OSCs) with vivid colors offer attractive prospects in aesthetical power‐generating windows. Unfortunately, they still suffer from certain limitations since the common approach for generating different colors is to adopt various photoactive layers, which complicates production processes and results in process‐induced performance deviations. Additionally, efficient ST‐OSCs with simultaneously improved average visible transmittance (AVT) and color rendering index (CRI) remain still challenging due to the trade‐off between photoelectric conversion efficiency (PCE) and AVT besides the interdependent/interactive relations of AVT and CRI. Herein, Ag/MoO3/Ag microcavity structure is introduced to delicately tune the absorption spectra of PM6:Y6 active material. The Ag/MoO3/Ag microcavity endows freely tunable colors to devices and meanwhile functions as a hole‐collecting layer. Under the guidance of optical simulation, the rationally designed ST‐OSCs with Ag/MoO3/Ag microcavity and Hf(ACB1)4 electron collection layer display good eye comfort colors (purple, sky blue, cyan, green, and magenta) independently of the inherent color of PM6:Y6 active material, and show a close to 12% PCE with an AVT of 23.69% and a CRI of 92.5 for cyan devices. This work provides a practical way for achieving efficient ST‐OSCs with simultaneously improved AVT and CRI, and using them in building‐integrated photovoltaics as multicolored photovoltaic glass windows.

Pseudo-Planar Heterojunction Organic Photovoltaics with Optimized Light Utilization for Printable Solar Windows.

The existing conformation of the active layer is defective for employment of semitransparent organic solar cells (ST-OSCs) in solar windows. Herein, scalable solar windows are successfully printed by introducing a pseudo-planar heterojunction (PPHJ) structure. The PPHJ structure can effectively improve the average visible transmittance (AVT) value while boosting the power conversion efficiency (PCE) of semitransparent devices due to the reduced optical loss. The universality of the PPHJ structure in the preparation of ST-OSCs is proved. Furthermore, an inset of a superhydrophobic patterned soft insertion layer (PSIL) in the encapsulated window improves the waterproof performance without losing transparency. Accordingly, the semitransparent devices based on the 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9-diundecyl-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2″,3″:4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile (Y6) system afford a maximal efficiency of 14.62%, with a considerable AVT of 20.42%, and the resultant solar windows achieve a stabilized efficiency of 13.34% with excellent waterproof performance. Moreover, the PCE of the unilateral broken solar windows retains 70.6% of the initial efficiency after being placed under simulated rainfall conditions for 1200 h at room temperature.

Fully solution-processed, light-weight, and ultraflexible organic solar cells

Organic photovoltaic (OPV) devices have the potential to be superior to other PV technologies for the use in applications that require very high flexibility or maximum specific power (power-per-weight ratio), such as textile integration, wearable electronics, or outer space applications. However, OPV devices also require encapsulation by barrier films to reduce the degradation driven by extrinsic factors, which in turn limits their flexibility and leads to lower specific power values. In this work, fully solution-processed (including both electrodes) semitransparent organic solar cells (OSCs) with performance comparable with conventional indium tin oxide-based devices are processed directly onto different barrier films of varying thicknesses. Direct cell fabrication onto barrier films leads to the elimination of the additional polyethylene terephthalate substrate and one of the two adhesive layers in the final stack of an encapsulated OPV device by replacing the industrial state-of-the-art sandwich encapsulation with a top-only encapsulation process, which yields significantly thinner and lighter ‘product-relevant’ PV devices. In addition to the increase of the specific power to 0.38 W g−1, which is more than four times higher than sandwich-encapsulated devices, these novel OSCs exhibit better flexibility and survive 5000 bending cycles with 4.5 mm bending radius. Moreover, the devices show comparable stability as conventionally encapsulated devices under constant illumination (1 sun) in ambient air for 1000 h. Finally, degradation under damp heat conditions (65 °C, 85% rh) was investigated and found to be determined by a combination of different factors, namely (UV) light soaking, intrinsic barrier properties, and potential damaging of the barriers during (laser) processing.

Using 3.0eV Large Bandgap Conjugated Polymer as Host Donor to Construct Ternary Semi-Transparent Polymer Solar Cells: Increased Average Visible Transmittance and Modified Color Temperature.

Although optical engineering strategy has been utilized to optimize average visible transmittance (AVT) of semi-transparent organic solar cells (ST-OSCs), judicious selection of active layer materials should be more direct and basic. Herein, an efficient ternary active layer is constructed with a wide bandgap (3.0eV) fluorescent polymer FC-S1 as host donor, a middle bandgap polymer PM6 as guest donor, and a narrow bandgap non-fullerene Y6-BO as acceptor. Using FC-S1 as the host donor can allow more visible photons to penetrate the device. In the absence of optical engineering, the ternary ST-OSC with FC-S1:PM6:Y6-BO=1:0.3:1.5 active layer of 30nm thickness displays a much higher AVT of 49.28% than that of 32.34% for a PM6:Y6-BO=1.3:1.5 based binary ST-OSC. The ternary ST-OSC provides a good power conversion efficiency of 6.01%, only slightly lower than 7.15% for the binary ST-OSC. The ternary ST-OSC also demonstrates a color rendering index (CRI) of 87 and a correlated color temperature (CCT) of 6916K, all better than CRI of 80 and CCT of 9022K for the binary ST-OSC. Moreover, the backbone of FC-S1 is mainly composed by fluorene and carbazole, two easily-accessible aromatic rings, which would meet low-cost concern of ST-OSCs.

Molecular Doping Increases the Semitransparent Photovoltaic Performance of Dilute Bulk Heterojunction Film with Discontinuous Polymer Donor Networks.

The semitransparent and colorful properties of organic solar cells (OSCs) attract intensive academic interests due to their potential application in building integrated photovoltaics, wearable electronics, and so forth. The most straightforward and effective method to tune these optical properties is varying the componential ratio in the blend film. However, the increase in device transmittance inevitably sacrifices the photovoltaic performance because of severe carrier recombination that originates from discontinuous charge-transport networks in the blend film. Herein, a strategy is proposed via the molecular-doping strategy to overcome these shortcomings. It is discovered that p-doping is able to release the trapped holes in segregated polymer domains leading to short-circuit current enhancement, while n-doping is more effective to fill the bandgap states producing a higher fill factor. More importantly, either type of doping improves the photovoltaic performance in the semitransparent photovoltaic devices. These discoveries provide a new pathway to breaking the compromise between the photovoltaic performance and optical transmittance in semitransparent OSCs, and hold promise for their future commercialization.

Using a Simple Optical Management Layer to Solve the Contradiction between Efficiency and Transmittance for Semitransparent Organic Solar Cells

Using a Simple Optical Management Layer to Solve the Contradiction between Efficiency and Transmittance for Semitransparent Organic Solar Cells

Recent Progress in Semitransparent Organic and Perovskite Solar Cells

Semitransparent organic and perovskite solar cells are considered promising photovoltaic (PV) devices that can be applied to power‐generating windows and facades of modern buildings and have achieved great progress in the past few years. Different from silicon‐based solar cells, the optical absorption of devices with organic and perovskite active layer materials can be easily tuned by modifying the chemical structure and adjusting the halide types or contents, respectively, to meet the demands of energy‐generating windows. In this review, the development progress of semitransparent PV (STPV) in terms of the selection of active layer materials, top transparent electrodes (TTEs), and strategies of enhancing the performance of STPVs is introduced. Meanwhile, the challenges and outlooks for the future development of STPVs are discussed.

Design of Near-Infrared Nonfullerene Acceptor with Ultralow Nonradiative Voltage Loss for High-Performance Semitransparent Ternary Organic Solar Cells.

Semitransparent organic solar cells (ST-OSCs) are considered as one of the most valuable applications of OSCs and a strong contender in the market. However, the optical band gap of current high-performance ST-OSCs is still not low enough to achieve the optimal balance between power conversion efficiency (PCE) and average visible transmittance (AVT). An N-substituted asymmetric nonfullerene acceptor SN with over 40 nm bathochromically shifted absorption compared to Y6 was designed and synthesized, based on which the device with PM6 as donor obtained a PCE of 14.3 %, accompanied with a nonradiative voltage loss as low as 0.15 eV. Meanwhile, ternary devices with the addition of SN into PM6 : Y6 can achieve a PCE of 17.5 % with an unchanged open-circuit voltage and improved short-circuit current. Benefiting from extended NIR absorption and lowered voltage loss, ST-OSCs based on PM6 : SN : Y6 were fabricated and the optimized device demonstrated a PCE of 14.0 % at an AVT of 20.2 %, which is the highest PCE at an AVT over 20 %.

Design of Near‐Infrared Nonfullerene Acceptor with Ultralow Nonradiative Voltage Loss for High‐Performance Semitransparent Ternary Organic Solar Cells

AbstractSemitransparent organic solar cells (ST‐OSCs) are considered as one of the most valuable applications of OSCs and a strong contender in the market. However, the optical band gap of current high‐performance ST‐OSCs is still not low enough to achieve the optimal balance between power conversion efficiency (PCE) and average visible transmittance (AVT). An N‐substituted asymmetric nonfullerene acceptor SN with over 40 nm bathochromically shifted absorption compared to Y6 was designed and synthesized, based on which the device with PM6 as donor obtained a PCE of 14.3 %, accompanied with a nonradiative voltage loss as low as 0.15 eV. Meanwhile, ternary devices with the addition of SN into PM6 : Y6 can achieve a PCE of 17.5 % with an unchanged open‐circuit voltage and improved short‐circuit current. Benefiting from extended NIR absorption and lowered voltage loss, ST‐OSCs based on PM6 : SN : Y6 were fabricated and the optimized device demonstrated a PCE of 14.0 % at an AVT of 20.2 %, which is the highest PCE at an AVT over 20 %.

Light Managements and Transparent Electrodes for Semitransparent Organic and Perovskite Solar Cells

Comparing with inorganic solar cells, organic solar cells and perovskite solar cells have attracted considerable attention owing to their unique properties such as the color tunability of their photoactive layers, low cost, catering to solution processing, and flexibility, which have been considered as the most promising technologies in wearable energy resources and show huge potential in fabricating transparent devices. In recent years, numerous light coupling constructions and transparent electrode optimization strategies have been applied to further enhance device photoelectric performance. In this review, common strategies focusing on light modulation and for semitransparent organic solar cells and semitransparent perovskite solar cells, which are crucial to increase Jsc, achieving adjustable chromaticity coordinates, high average visible transmittance and color rendering index have been summarized in detail.

Semitransparent organic solar cells: from molecular design to structure–performance relationships

Semitransparent organic solar cells (ST-OSCs) have potential for the next generation of power windows, buildings and green house because of their transparency, color tunability, aesthetics, and diverse functionalities with reduced cost.

A near-infrared polymer enables over 50% transmittance in semi-transparent organic solar cells

A semi-transparent organic solar cell achieves an over 50% average visible transmittance, which is attributed to the rational design of the polymer donor with extended absorption in the near-infrared region.

A molecular weight-regulated sequential deposition strategy enabling semitransparent organic solar cells with the light utilization efficiency of over 5%

In this work, a molecular weight-regulated efficient SD strategy is firstly employed to improve the performance of the ST-OSCs. More importantly, the light utilization efficiency (LUE) of 5.01% is obtained.

High-performance semitransparent organic solar cells enabled by pseudo-planar heterojunction structures combined with optical engineering

PPHJ ST-OSCs combined with optical engineering achieved an impressive PCE of 13.1% and an AVT of 27.8%, which is the highest value at an AVT of over 25%.

Solution-Processed Highly Efficient Semitransparent Organic Solar Cells with Low Donor Contents

Semitransparent organic solar cells (ST-OSCs) are promising candidates for applications in building-integrated photovoltaics (BIPV) as windows and facades. The challenge to achieve highly efficient ST-OSCs is the trade-off between power conversion efficiency (PCE) and average visible transmittance (AVT). Herein, solution-processed ST-OSCs are demonstrated on the basis a polymer donor, PM6, and a small molecule acceptor, Y6; lowering the visible-absorbing PM6 contents in blends could increase AVT and maintain PCE. Additionally, conductive polymer PEDOT:PSS is used as the top electrode due to its high transparency, good conductivity, and solution processability. Efficient ST-OSCs with 20 wt % PM6 achieve high PCE of 7.46% and AVT of 36.4%. The light utilization efficiency (LUE) of 2.72% is among the best reported values for solution-processed ST-OSCs. This work provides a straightforward approach for solution-processed ST-OSCs by combining a low fraction of visible-wavelength-selective polymer donors with near-infrared nonfullerene acceptors to achieve high PCE and AVT simultaneously.

High‐Performance Semitransparent Organic Solar Cells Enabled by Improved Charge Transport and Optical Engineering of Ternary Blend Active Layer

Semitransparent organic solar cells (STOSCs) make the industrialization of power‐generating windows a reality with promising average visible transmittance (AVT) and rapidly increased power conversion efficiencies (PCEs). To achieve the ultimate goal, improving the efficiency of STOSCs without degrading the transparency in visible range is critical. Herein, a nonfused ring acceptor (BDC‐4F‐C8) by alkyl chain engineering is used as third component for ternary blend active layer to enhance the electrical and optical properties of STOSCs. With optimizing the proportion of third component, STOSCs with ternary active layer exhibit improved open‐circuit voltage, short‐circuit current, and fill factor, which leads to the best PCE of 13.19% with AVT of 24.56%, while the PCE of opaque one is 17.02%. This work presents an effective strategy to achieve high‐performance ternary STOSCs with high AVT employing a low‐cost nonfused ring electron acceptor material, and manifests how the third component affects the optical features of a ternary active layer to achieve efficient semitransparent devices.

Smart and Solar Greenhouse Covers: Recent Developments and Future Perspectives

The examination of recent developments and future perspectives on smart and solar greenhouse covers is significant for commercial agriculture given that traditional greenhouse relied on external energy sources and fossil fuels to facilitate lighting, heating and forced cooling. The aim of this review article was to examine smart and solar materials covering greenhouse. However, the scope was limited to intelligent PhotoVoltaic (PV) systems, optimization of some material properties including smart covers, heat loading and the use of Internet of Things (IoT) to reduce the cost of operating greenhouse. As such, the following thematic areas were expounded in the research; intelligent PV systems, optimization of the Power Conversion Efficiency (PCE), Panel Generator Factor (PGF) and other material properties, heat loading future outlook and perspectives. The intelligent PV section focused on next-generation IoT and Artificial Neural Networks (ANN) systems for greenhouse automation while the optimization of material parameters emphasized quantum dots, semi-transparent organic solar cells, Pb-based and Pb-based PVs and three dimensional (3D) printing. The evaluation translated to better understanding of the future outlook of the energy-independent greenhouse. Greenhouse fitted with transparent PV roofs are a sustainable alternative given that the energy generated was 100% renewable and economical. Conservative estimates further indicated that the replacement of conventional sources of energy with solar would translate to 40–60% energy cost savings. The economic savings were demonstrated by the Levelized cost of energy. A key constraint regarded the limited commercialization of emerging innovations, including transparent and semitransparent PV modules made of Pb-quantum dots, and amorphous tungsten oxide (WO3) films, with desirable electrochromic properties such as reversible color changes. In addition to intelligent energy harvesting, smart IoT-based materials embedded with thermal, humidity, and water sensors improved thermal regulation, frost mitigation and prevention, and the management of pests and disease. In turn, this translated to lower post-harvest losses and better yields and revenues.

Nanoporous Polymer Reflectors for Organic Solar Cells

Due to their high transparency, electrodes fabricated from conductive polymers are often implemented in semitransparent organic solar cells. Opaque solar cells usually employ metal back electrodes with high reflectivity for best photon confinement in the light‐harvesting layer. Herein, a bilayer back electrode comprising conductive polymers and nanofoamed poly(methyl methacrylate) (PMMA) is investigated, the latter of which creates diffuse reflection of the incoming light. By tuning the thickness of the nanofoamed PMMA layer, absorption and transmission of the solar cells can be tailored from opaque to vastly transparent. Due to its diffusive character, this versatile electrode enhances the light absorption in the wavelength regimes with lower absorption coefficient. The solar cells are particularly suited for deployment in frosted window applications.

Towards a bright future: The versatile applications of organic solar cells

Due to the mechanical flexibility, light weight, aesthetics, absorption tunability and environmental friendliness, organic solar cells (OSCs) have superior application potential over their inorganic counterparts including silicon and perovskite solar cells (PSCs). Thanks to these benefits, the past decade have witnessed the rapid growth of flexible OSCs, semitransparent OSCs and indoor OSCs. In this progress report, we firstly overview the recent advance of the applications of the three promising OSCs. Subsequently, we sketch the critical points for the three classes of OSCs and highlight the efforts paid by the research community to address these issues. Besides, we discuss some popular strategies to afford great performance of each kind of OSC, respectively, and underline the corresponding breakthrough directions. Last but not least, we present the remaining challenges for advancing the commercial applications of these three classes of OSCs.