Ideal microlens array based on polystyrene microspheres for light extraction in organic light-emitting diodes

Zhou, Jiankang; Hua, Xiao-Chen; Huang, Chen-Chao; Sun, Qi; Fung, Man‐Keung

doi:10.1016/j.orgel.2019.03.051

Cited by 17 publications

(2 citation statements)

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“…Recent development in the field of light extraction has produced different highly efficient solutions, both in optimizing OLED internal and external optical losses -see for example the latest reviews on light outcoupling solutions in OLEDs [1,11,12]. In particular, much research has been done to limit substrate losses by attaching microlenses [13][14][15][16], scattering films [17][18][19][20], introducing scattering particles [21], or using microtextures [22][23][24][25]. These solutions provide high improvements at low cost and, generally, do not affect the electrical properties of the sensitive organic layers.…”

Section: Introductionmentioning

confidence: 99%

Opto-Electronics Review

Kovačič

2022

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External light outcoupling structures provide a cost-effective and highly efficient solution for light extraction in organic light-emitting diodes. Among them, different microtextures, mainly optimized for devices with isotopically oriented emission dipoles, have been proposed as an efficient light extraction solution. In the paper, the outcoupling for a preferential orientation of emission dipoles is studied for the case of a red bottom-emitting organic light-emitting diode. Optical simulations are used to analyse the preferential orientation of dipoles in combination with three different textures, namely hexagonal array of sine-textures, three-sided pyramids, and random pyramids. It is shown that while there are minimal differences between the optimized textures, the highest external quantum efficiency of 51% is predicted by using the three-sided pyramid texture. Further improvements, by employing highly oriented dipole sources, are examined. In this case, the results show that the top outcoupling efficiencies can be achieved with the same texture shape and size, regardless of the preferred orientation of the emission dipoles. Using an optimized three-sided pyramid in combination with ideally parallel oriented dipoles, an efficiency of 62% is achievable. A detailed analysis of the optical situation inside the glass substrate, dominating external light outcoupling, is presented. Depicted results and their analysis offer a simplified further research and development of external light extraction for organic light-emitting devices with highly oriented dipole emission sources.

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Section: Introductionmentioning

confidence: 99%

Opto-Electronics Review

Kovačič

2022

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“…Microlens arrays (MLAs) and MLA-based artificial compound eyes (ACEs) play a key role in advanced micro-optical systems (Pan et al, 2007 ; Song et al, 2013 ; Gorzelak et al, 2014 ; Petsch et al, 2016 ; Lin et al, 2018 ). By taking advantages of small size, high integration, and striking optical capability, MLAs and ACEs are widely applied in light-field regulation (Deng et al, 2014 ; Wei et al, 2018 ; Zhou et al, 2018 ; Sohna et al, 2019 ), fiber coupling (Elsherif et al, 2019 ; Liu et al, 2019 ; Orth et al, 2019 ), lab-on-chip devices (Fei et al, 2011 ; Lv et al, 2016 ; Vespini et al, 2016 ), biochemical observation (Ma et al, 2014 ; Holzner et al, 2018 ), laser microfabrication (Bekesi et al, 2010 ; Li et al, 2020 ), solar cells (Chen Y. et al, 2013 ), sensors (Zanella et al, 2020 ), three-dimensional imaging (Li et al, 2016 ; Kim et al, 2019 ; Zhang et al, 2019 ; Joo et al, 2020 ; Qin et al, 2020 ; Zhao et al, 2020 ), and light extraction (Shin et al, 2018 ; Zhou et al, 2019a , b ). However, the normal use of the MLA is usually restricted by many limitations.…”

Section: Introductionmentioning

confidence: 99%

Mini-Review on Bioinspired Superwetting Microlens Array and Compound Eye

et al. 2020

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Microlens arrays (MLAs) and MLA-based artificial compound eyes (ACEs) are the important miniaturized optical components in modern micro-optical systems. However, their optical performance will seriously decline once they are wetted by water droplets (such as fog, dew, and rain droplets) or are polluted by contaminations in a humid environment. In this mini-review, we summarize the research works related to the fabrication of superwetting MLAs and ACEs and show how to integrate superhydrophobic and superoleophobic microstructures with an MLA. The fabrication strategy can be split into two categories. One is the hybrid pattern composed of the MLA domain and the superwetting domain. Another is the direct formation of superwetting nanostructures on the surface of the microlenses. The superhydrophobicity or superoleophobicity endows the MLAs and ACEs with liquid repellence and self-cleaning function besides excellent optical performance. We believe that the superwetting MLAs and ACEs will have significant applications in various optical systems that are often used in the humid or liquid environment.

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Bioinspired Artificial Compound Eyes: Characteristic, Fabrication, and Application

Yang

Bian

et al. 2021

Adv Materials Technologies

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the visual nerve perception. This type of eyes has ultrahigh resolution, which can get clear image information. Inspired by this imaging system, people have put significant efforts over a long time for development of camera-related optical system for various applications, such as endoscope, digital camera, smartphones, robot eyes, visual implants. [7][8][9][10] Because of the rapid progress in micro/nano technologies, the artificial eyes structures can achieve extremely high resolution that is close to or even exceeding the human eye. However, the low field of view (FOV) (the maximum value is only 90°) hinders its wider applications. To solve this problem, multiple cameras need to be put together to work, which not only increases the cost, but also makes the entire optical system cumbersome. Hence, an optical device with portable, integrated, and large FOV features is highly desired.Different from the single-lens eyes, the insect eyes adopt another visual system. Figure 1b shows a honeybee's apposition compound eye, which has thousands of ommatidia arranged on a curved surface so that each ommatidium points in different directions. [11] Each unit consists of a lens, a crystalline cone, and a rhabdom. The focused light signal is transmitted to the photosensitive area by the crystalline cone, and then visual perception is generated after passing through the rhabdom. Each of the ommatidium can image which enables the insects to obtain sufficient information in a complex environment and exhibits the characteristics of large FOV, low aberration, and high sensitivity to moving objects. [12] In addition to the honeybee's compound eyes, the eyes of other insects in nature, such as mosquito eye, [13] fly's eye, [14] moth's eye, [15] and dragonfly's eye [16] also have similar structure and have attracted much attention due to the deep research on bionics. [4,9,12,[17][18][19][20][21] The characteristics of the compound eyes in nature and the advanced micro/nano-processing technologies provide great technical support and inspiration for the researchers to prepare artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) as optical imaging elements. [22][23][24][25][26][27][28][29][30] Such MLAs compose of microscale lenses with the same surface feature and the regular arrangements are important microoptical components. The great light field (LF) regulation and focusing abilities of MLAs have made it essentially in various applications such as imaging, [31][32][33][34][35][36][37][38][39] dynamic target capture, [40][41][42] beaming homogenizing, [43][44][45][46] sensing, [47][48][49] light extractionThe natural compound eyes provide great inspiration for design of advanced imaging devices. Artificial compound eyes (ACEs) with close-packed microlens arrays (MLAs) have attracted enormous research interests due to their remarkable advantages in modern micro-optical systems, such as miniaturization, high integration, tunable focal length, large field of view, and moving objects tracking. Over a decade of intens...

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Ideal microlens array based on polystyrene microspheres for light extraction in organic light-emitting diodes

Cited by 17 publications

References 30 publications

Opto-Electronics Review

Opto-Electronics Review

Mini-Review on Bioinspired Superwetting Microlens Array and Compound Eye

Bioinspired Artificial Compound Eyes: Characteristic, Fabrication, and Application

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