Design and fabrication of a semi-transparent solar cell considering the effect of the layer thickness of MoO3/Ag/MoO3 transparent top contact on optical and electrical properties

Solution Processed Semi-Transparent Organic Solar Cells Over 50% Visible Transmittance Enabled by Silver Nanowire Electrode with Sandwich Structure

Photovoltaic windows with easy installation for the power supply of household appliances have long been a desire of energy researchers. However, due to the lack of top electrodes that offer both high transparency and low sheet resistance, the development of high-transparency photovoltaic windows for indoor lighting scenarios has lagged significantly behind photovoltaic windows where privacy issues are involved. Addressing this issue, this work develops a solution-processable transparent top electrode using sandwich structure silver nanowires, realizing high transparency in semi-transparent organic solar cells. The wettability and conducting properties of the electrode are improved by a modified hole-transport layer named HP. The semi-transparent solar cell exhibits good see-through properties at a high average visible transmittance of 50.8%, with power conversion efficiency of 7.34%, and light utilization efficiency of 3.73%, which is the highest without optical modulations. Moreover, flexible devices based on the above-mentioned architecture also show excellent mechanical tolerance compared with Ag electrode counterparts, which retains 94.5% of their original efficiency after 1500 bending cycles. This work provides a valuable approach for fabricating solution-processed high transparency organic solar cells, which is essential in future applications in building integrated photovoltaics.

Photopically Transparent Organic Solar Cells with Tungsten Oxide-Based Multilayer Electrodes

The tailoring of the average photopic transmittance (APT) of transparent organic solar cells (T-OSCs) has been the greatest challenge in building-integrated photovoltaic applications for future smart solar windows to regulate indoor brightness, maintain a human circadian rhythm, and positively impact human emotions by allowing the observation of the external environment. However, a notorious trade-off exists between the APT and power conversion efficiency (PCE) of T-OSCs, mainly due to the absence of highly conductive and transparent top electrodes, which are a key building block determining the PCE and APT. Herein, we demonstrate a new tungsten oxide (WO3)-based multilayer as a highly conductive and transparent top electrode that provides an excellent APT while maintaining a high PCE in T-OSCs. With the assistance of optical simulation based on a transfer matrix method to calculate the optimum thicknesses of the multilayer electrodes, we achieve the best-performing T-OSC with a PCE of 7.0% and a full device APT of 46.7%, resulting in a high light utilization efficiency of 3.27%, which is superior to that of T-OSCs based on the same photoactive system. Furthermore, superior thermal stability at 85 °C in an N2 atmosphere is observed in WO3-based T-OSCs, maintaining 98% of the initial PCE after about 231 h. Our findings provide new insights into the development of T-OSCs with high efficiency and transparency.

In-depth analysis on PTB7 based semi-transparent solar cell employing MoO3/Ag/WO3 contact for advanced optical performance and light utilization

Novel semi-transparent organic solar cells (ST-OSC) can be designed with high average visible transmittance (AVT) while at the same time exhibiting superior photovoltaic performance. This reach requires their design to be based not only on conventional window applications but also on functional industrial applications that require exceptional optical performance. In ST-OSC, high AVT can be achieved by photonic-based dielectric/metal/dielectric (DMD) transparent contact engineering. Functional optical modification can also be made with a fine-tuned design of DMD that includes a light management engineering-based approach. Thus, ST-OSCs can be suitable for aesthetic, colourful and decorative industrial windows that provide natural lighting. In this study, we determined optimal ST-OSCs based on a novel PTB7:PC₇₁BM polymer blend with MoO₃/Ag/WO₃ asymmetric DMD top contact by examining extraordinary optical properties such as AVT, colour rendering index, correlated colour temperature and colour perception over 10 thousand designs. In addition to determining the optimality and extraordinary optical limits for PTB7, we also evaluated the photon-harvesting and photovoltaic performance of ST-OSCs from external quantum efficiency and quantum utilization efficiency. In optimal situations, ST-OSCs offering 48.75% AVT, 99.08 CRI, and sky-blue colours were designed and determined to generate short-circuit current densities of 9.88 mA·cm^-2, 13.64 mA·cm^-2, and 13.06 mA·cm^-2, respectively.

Tailoring optimal translocation conditions towards proximity of borotellurite glasses to the red spectrum through CeO2 for practical applications

We report the critical optical properties such as Average Visible Transmittance (AVT), colour, Color Rendering Index (CRI), and Correlated Color Temperature (CCT) of a multicomponent glass system with a nominal composition of 50TeO₂-30B₂O₃-(20-x)Li₂O-xCeO₂ (x = 0,0.5,1,2,3,4,5,10,15,20 mol%). Various advanced theoretical approaches as well as calculations are utilized in terms of determining the optical properties of studied glasses. The maximum transmittance and AVT values of the glass system exceeded 80% and 79.59%, respectively. The colour coordinates are found extremely near to D65 and the achromatic point without CeO₂ contribution. According to our results, the current system has a promising ability to be utilized for coloured window applications in terms of both AVT and colour with 2% CeO₂ doping. Our results showed that, the CeO₂ additive is able to move the glass colour straight into the red spectrum by shifting the transmittance spectrum to the long-wavelength portion of the visible spectrum. With 10% CeO₂ doping, opacity in the visible area and permeability in the NIR region are obtained, and the CCT value changes from 5002 K to 2560 K. It can be concluded that a filter system with modifiable NIR or red optical characteristics may be produced through the CeO₂ alterations in borotellurite glass systems.

Enhancement of color and photovoltaic performance of semi-transparent organic solar cell via fine-tuned 1D photonic crystal

Semi-transparent organic solar cells’ (ST-OSCs) photovoltaic and high optical performance parameters are evaluated in innovative applications such as power-generating windows for buildings, automobiles, and aesthetic designs in architectural and industrial products. These parameters require the precision design of structures that optimize optical properties in the visible region and aim to achieve the required photon harvest in UV and IR. These designs can be realized by integrating wavelength-selective photonics-based systems into ST-OSC to increase localized absorption in wavelengths greater than 600 nm and NIR and provide modifiable optical properties. In this study, methodologically, we followed highly detailed light management engineering and transfer matrix method-based theoretical and experimental approaches. We discussed the optimal structures by evaluating color, color rendering index, correlated color temperature, and photovoltaic performances for ST-OSCs, including one-dimensional photonic crystal (1D-PC) designed at different resonance wavelengths (λ_B) and periods. Finally, by integrating fine-tuned (MgF₂/MoO₃)^N 1D-PC, we report the inherently dark purple-red color of the P3HT:PCBM bulk-heterojunction-based ST-OSC neutralizes with the optimal state was 0.3248 and 0.3733 by adjusting close to the Planckian locus. We also enhanced short current density from 5.77 mA/cm² to 6.12 mA/cm² and PCE were increased by 7.34% from 1.77% to 1.90% designed for the N = 4 period and λ_B = 700 nm.

The role of structural parameters on efficiency and transparency of semi-transparent non-fullerene organic solar cell

Semitransparent organic solar cells have become attractive recently because of their photon harvesting in the near-infrared and ultraviolet range and passing in the visible light region. Semitransparent organic solar cells with ITO/ZnO/PBDB-T:ITIC/MoO3/Ag/MoO3 structure have been studied in this work and the effects of PBDB-T:ITIC active layer thicknesses and the transparent top electrode, MoO₃/Ag/MoO₃, thickness on the solar cell performance such as I-V characteristics, the power conversion efficiency, the average visible transmittance, and the color coordinates in the CIE color space are investigated. The drift–diffusion model, including the density of exactions, and their displacement is used to model the devices. The model is examined with experimentally reported devices, where there is a very good agreement between them, then is applied to the new structures. The obtained results show that the average visible transmittance of more than 45% is achievable for these structures with reasonable power conversion efficiency.

Highly improved light harvesting and photovoltaic performance in CdTe solar cell with functional designed 1D-photonic crystal via light management engineering

Photonic-based functional designs and integrations for advanced optoelectronic devices are regarded as promising candidates considering the enhancement of efficiency and tunability. With the aim to improve photovoltaic performance by increasing photon harvesting, the study presents the prominent findings of experimental and theoretical comparison of optical and electrical evaluation integrating a functionally designed one-dimension photonic crystal (1D-PC) into CdTe solar cells. Since transparency of the CdS/CdTe heterojunction based solar cell (SC) is reduced by a photonic band gap formed by (MgF₂/MoO₃)^N 1D-PC; namely, re-harvesting is improved by increasing absorbance. The period number at resonance wavelength of 850 nm and photocurrent density (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${J}_{ph}$$\end{document}Jph) have remarkable influence on the investigation. For four periods, the reflectance in the region of photonic band gap is sufficient for photon harvesting and saturation occurs. The photovoltaic performances are comparatively analysed for SCs with and without 1D-PC produced at optimal values. The open-circuit voltage does not change, besides, short-circuit current density and maximum-current density vary between 15.86–17.23 mA cm⁻² and, 13.08–15.41 mA cm⁻². Having integrated the 1D-PC into the structure, it is concluded that the FF and power conversion efficiency increase from 55.27 to 63.35% with an improvement of 15.91% and, from 8.26 to 10.47% with an improvement of 21.10%.

Functional optical design of thickness-optimized transparent conductive dielectric-metal-dielectric plasmonic structure

Dielectric/metal/dielectric plasmonic transparent structures play an important role in tailoring the high-optical performance of various optoelectronic devices. Though these structures are in significant demand in applications, including modification of the optical properties, average visible transmittance (AVT) and colour render index (CRI) and correlated colour temperature (CCT), obtaining optimal ones require precise thickness optimization. The overall objective of this study is the estimation of the optimal design concept of MoO₃/Ag/WO₃ (10/d_Ag/d_WO3 nm) plasmonic structure. To explore the proper use in optoelectronic devices, we are motivated to conduct a rigorous optical evaluation on the thickness of layers. Having calculated optical characteristics and achieved the highest AVT of 97.3% for d_Ag = 4 nm and d_WO3 = 6 nm by the transfer matrix method, it is quite possible to offer the potential of the structure acting as a transparent contact. Notably, the colour coordinates of the structure are x = 0.3110 and y = 0.3271, namely, it attributes very close to the Planckian locus. This superior colour performance displays that MoO₃/Ag/WO₃ shall undergo rapid development in neutral-colour windows and LED technologies. Structure with d_Ag = 6 nm and d_WO3 = 16 nm exhibits the highest CRI of 98.58, thus identifying an optimal structure that can be integrated into LED lighting applications and imaging technologies. Besides the colour of structure with d_Ag = 4 nm and d_WO3 = 8 nm is equal for D65 Standard Illuminant, the study reports that the range of CCTs are between 5000 and 6500 K. This optimization makes the structure employable as a near-daylight broadband illuminant. The study emphasizes that optimal MoO₃/Ag/WO₃ plasmonic structures can be used effectively to boost optoelectronic devices' performance.

Theory-Guided Material Design Enabling High-Performance Multifunctional Semitransparent Organic Photovoltaics without Optical Modulations

Semitransparent organic photovoltaics (ST-OPVs) have drawn great attention for promising applications in building-integrated photovoltaics, providing additional power generation for daily use. A previously proposed strategy, "complementary NIR absorption," is widely applied for high-performance ST-OPVs. However, rational material design toward high performance has not been achieved. In this work, an external quantum efficiency (EQE) model describing this strategy is developed to explore the full potential of material design on ST-OPV performance. Guided by the model, a novel nonfullerene acceptor (NFA), ATT-9, is designed and synthesized, which possesses optimal bandgap for ST-OPVs, achieving a record short-circuit current density of 30 mA cm^-2 and a power conversion efficiency of 13.40%, the highest value among devices based on NFAs with bandgaps lower than 1.2 eV. It is notworthy that, at such a low bandgap, the energy loss of the device is only 0.58 eV, which is attributed to the low energetic disorder confirmed by an ultralow Urbach energy of 21.6 meV. Benefiting from the optimal bandgap and low energy loss, the ATT-9-based ST-OPV achieves a high light utilization efficiency of 3.33% without optical modulations, and meanwhile shows excellent thermal insulation, exceeding the commercial 3M heat-insulating window film, demonstrating the outstanding application prospects of multifunctional ST-OPVs.