Low‐Temperature‐Processed 9% Colloidal Quantum Dot Photovoltaic Devices through Interfacial Management of p–n Heterojunction

Azmi, Randi; Aqoma, Havid; Hadmojo, Wisnu Tantyo; Yun, Jin Mun; Yoon, Soyeon; Kim, Kyungkon; Rag, Young; Oh, Seung Hwan; Jang, Sung‐Yeon

doi:10.1002/aenm.201502146

Cited by 73 publications

(80 citation statements)

References 48 publications

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“…[27,28] The HOMO levels of polymer HTLs were appropriate to extract holes from i-CQDs, while the LUMO levels of polymer HTLs were sufficiently high to block electron back transfer from i-CQDs. [3,16] For the fabrication of photoactive layers, i-CQD ink was directly spin-coated onto ZnO ETLs without additional coating or SSE steps. Compared to P3HT, the PTB7 possesses a deeper Fermi level and HOMO level, which are favorable to extract holes from i-CQD to HTLs.…”

Section: Resultsmentioning

confidence: 99%

“…Energy Mater. While the effects of interfacial dipoles at ETL/CQD interfaces are relatively well documented, [8,16,17] photoinduced dipole effects of polymer HTLs in CQDPVs have never been reported. [50] The photoinduced alignment of dipoles in PTB7 reduced the charge accumulation and recombination at the perovskite/PTB7 interfaces.…”

Section: Resultsmentioning

confidence: 99%

“…[16] The CQD active layers were fabricated by spin-coating of i-CQD ink, synthesized following the reported method, [3] at ≈1000 rpm for 90 s on ZnO ETLs to achieve a thickness of ≈380 nm. The ZnO ETLs were prepared on ITO/glass by following the previously reported method.…”

Section: Methodsmentioning

confidence: 99%

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Improved Processability and Efficiency of Colloidal Quantum Dot Solar Cells Based on Organic Hole Transport Layers

Aqoma

Mubarok

Lee

et al. 2018

Advanced Energy Materials

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IntroductionColloidal quantum dot (CQD) based photovoltaic devices (CQDPVs) have emerged as promising next-generation solar cells owing to low-cost solution processibility at low temperature, easy bandgap tunability into the near infrared (NIR, λ > 800 nm) regime, and multiple exciton generation. [1,2] The power conversion efficiency (PCE) of CQDPVs has improved High-efficiency solid-state-ligand-exchange (SSE) step-free colloidal quantum dot photovoltaic (CQDPV) devices are developed by employing CQD ink based active layers and organic (Polythieno[3,4-b]-thiophene-co-benzodithiophene (PTB7) and poly(3-hexylthiophene) (P3HT)) based hole transport layers (HTLs). The device using PTB7 as an HTL exhibits superior performance to that using the current leading organic HTL, P3HT, because of favorable energy levels, higher hole mobility, and facilitated interfacial charge transfer. The PTB7 based device achieves power conversion efficiency (PCE) of 9.60%, which is the highest among reported CQDPVs using organic HTLs. This result is also comparable to the PCE of an optimized device based on a thiol-exchanged p-type CQD, the current-state-of-the-art HTL. From the viewpoint of device processing, the fabrication of CQDPVs is achieved by direct single-coating of CQD active layers and organic HTLs at low temperature without SSE steps. The experimental results and device simulation results in this work suggest that further engineering of organic HTL materials can open new doors to improve the performance and processing of CQDPVs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Improved Processability and Efficiency of Colloidal Quantum Dot Solar Cells Based on Organic Hole Transport Layers

Aqoma

Mubarok

Lee

et al. 2018

Advanced Energy Materials

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“…[12][13][14][15][16] However, ZnO is used less often than mesoporous TiO 2 because it has several drawbacks. Planar heterojunctionstructured PSCs have also been widely investigated because they enable adoption of low-temperature electron accepting layers (EALs).…”

mentioning

confidence: 99%

High‐Efficiency Low‐Temperature ZnO Based Perovskite Solar Cells Based on Highly Polar, Nonwetting Self‐Assembled Molecular Layers

Azmi

Hadmojo

Sinaga

et al. 2017

Advanced Energy Materials

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154

164

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electron-accepting TiO 2 scaffolds require a high-temperature annealing process (≈500 °C), which limits their use with flexible substrates. Planar heterojunctionstructured PSCs have also been widely investigated because they enable adoption of low-temperature electron accepting layers (EALs). Zinc oxide, ZnO, is a strong EAL candidate because it offers good electrical properties even when prepared at low temperatures. [12][13][14][15][16] However, ZnO is used less often than mesoporous TiO 2 because it has several drawbacks. The surface properties of the ZnO layers are not favorable for growth of uniform perovskite layers with large crystal grains. This affects device performance significantly. [2,3,[7][8][9][10]17] Thus, efforts have been undertaken to improve perovskite layer quality by enhancing ZnO surface hydrophobicity. [18][19][20][21] Another shortcoming is the reverse reaction from perovskite to PbI 2 that can occur at ZnO/perovskite interfaces during perovskite layer formation. [14,[22][23][24] Two-step sequential deposition method has been employed to fabricate perovskite active layers on ZnO-EALs. This results in more reproducible synthesis of continuous, pinholefree perovskite layers than conventional single deposition methods. [15,21,[25][26][27][28][29] The perovskite layers in these reports were formed in two steps: (i) PbI 2 layer formation and (ii) perovskite layer formation, which occurred when the PbI 2 layer was immersed into an alkyl-ammonium iodide solution and annealed (80-100 °C). The sequential deposition method partially alleviated the burden of the reverse reaction that occurs at ZnO/perovskite interfaces, while helping to achieve a PCE of ≈16%. [15,30] Thus, the development of these strategies may offer a chance to further enhance low-temperature ZnO based PSC performance.Herein, we present high-efficiency, low-temperature PSCs using a strategy that combines self-assembled monolayer (SAM) modification of ZnO-EALs with sequential preparation of perovskite active layers. SAMs of the newly synthesized, highly polar molecules were constructed on ZnO-EALs and the perovskite layers were formed via sequential deposition. The SAMs acted as ZnO wetting control layers and as electric dipole layers. [1,13,19,20,[31][32][33] Modifying our SAMs enhanced the hydrophobicity of ZnO, which improved perovskite formation quality. Simultaneously, the electric dipole effect induced via Herein, this study reports high-efficiency, low-temperature ZnO based planar perovskite solar cells (PSCs) with state-of-the-art performance. They are achieved via a strategy that combines dual-functional self-assembled monolayer (SAM) modification of ZnO electron accepting layers (EALs) with sequential deposition of perovskite active layers. The SAMs, constructed from newly synthesized molecules with high dipole moments, act both as excellent surface wetting control layers and as electric dipole layers for ZnO-EALs. The insertion of SAMs improves the quality of PbI 2 layers and final perovskite layers during sequential dep...

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“…Zinc oxide (ZnO) is a n-type semiconducting material with a great application potential as electron conduit in (opto) electronic devices [1,2], photocatalysts [3,4], and photoluminescence materials [5,6]. ere are several methods for the synthesis of ZnO nanostructures, including sol-gel method, controlled precipitation, solvothermal techniques, microemulsion, and sonochemical treatments [7].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Red Emission in Ultrasound-Assisted Sol-Gel Derived ZnO/PMMA Nanocomposite

Mai

Hoang

Dũng

2018

Advances in Materials Science and Engineering

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Cost-effective methods for preparing ZnO nanostructures are of importance for the deployment of ZnO in many applications including n-type conduits, catalysts, nanophosphor, and optoelectronics. Herein, we present a room-temperature sol-gel method with the aid of ultrasonication to prepare white-emitting ZnO nanoparticles (NPs). X-ray diffraction and electron microscopic analyses revealed that the size and shape of ZnO NPs can be controlled simply by changing the concentration of the Zn precursor.e ZnO NPs had a broad photoluminescence emission, ranging from 450 nm to 800 nm, while their composite in PMMA matrix showed an enhancement in the red region induced by ZnO-PMMA interfacial band-bending effects. e results demonstrated herein promise a simple tool for control over size, shape, and emission of ZnO materials for diverse applications.

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Low‐Temperature‐Processed 9% Colloidal Quantum Dot Photovoltaic Devices through Interfacial Management of p–n Heterojunction

Cited by 73 publications

References 48 publications

Improved Processability and Efficiency of Colloidal Quantum Dot Solar Cells Based on Organic Hole Transport Layers

Improved Processability and Efficiency of Colloidal Quantum Dot Solar Cells Based on Organic Hole Transport Layers

High‐Efficiency Low‐Temperature ZnO Based Perovskite Solar Cells Based on Highly Polar, Nonwetting Self‐Assembled Molecular Layers

Enhanced Red Emission in Ultrasound-Assisted Sol-Gel Derived ZnO/PMMA Nanocomposite

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