Finely Interpenetrating Bulk Heterojunction Structure for Lead Sulfide

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Letter

Finely Interpenetrating Bulk Heterojunction Structure for Lead Sulfide Colloidal Quantum Dot Solar Cells by Convective Assembly Guozheng Shi, Anusit Kaewprajak, Xufeng Ling, Akinobu Hayakawa, Sijie Zhou, Bin Song, YangWon Kang, Takahiro Hayashi, Mutlu Altun, Masahiro Nakaya, Zeke Liu, Haibin Wang, Takashi Sagawa, and Wanli Ma ACS Energy Lett., Just Accepted Manuscript • Publication Date (Web): 26 Mar 2019 Downloaded from http://pubs.acs.org on March 26, 2019

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ACS Energy Letters

Finely Interpenetrating Bulk Heterojunction Structure for Lead Sulfide Colloidal Quantum Dot Solar Cells by Convective Assembly

Guozheng Shi,†‡ Anusit Kaewprajak,‡ Xufeng Ling,† Akinobu Hayakawa,‡ Sijie Zhou,† Bin Song,† YangWon Kang,‡ Takahiro Hayashi,‡ Mutlu Ege Altun,‡ Masahiro Nakaya,‡ Zeke Liu,† Haibin Wang,§ Takashi Sagawa‡* and Wanli Ma†*

† Jiangsu Key Laboratory for Carbon-Based Functional Materials and Devices Institute of Functional Nano and Soft Materials (FUNSOM), Soochow University Suzhou, Jiangsu 215123, China. ‡ Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto, 606-8501, Japan. § Research Center for Advanced Science and Technology, The University of Tokyo, 153-8904 Tokyo, Japan

* Corresponding authors. Email: [email protected], [email protected].

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In paving the way toward low-cost, highly efficient and stable photovoltaics, lead chalcogenides colloidal quantum dot (PbS CQD) is one of the most promising materials that possesses the features of easily engineered physical properties and solution processibility.1-4 Benefitted from their large exciton Bohr radius and specific surface area, PbS CQDs embody numerous superiorities over conventional bulk materials such as size-dependent bandgap, tunable surface chemical modification along with flexibility in device engineering and low-temperature processing, which boost the development of both single and tandem QDs solar cells.5-9 A highest power conversion efficiency (PCE) of 12% with remarkable air stability has been demonstrated recently,10 whereas a huge gap still exists between experimental device performance and theoretical efficiency of 45% for single junction solar cell coupled with multiple exciton effects.11 The limited charge carrier diffusion length within a range of 80-300 nm is one of the limitations for CQDs which falls short of the proper thickness of PbS CQDs active layers,12-14 which should be more than 1 J

to fully

utilize the incident light energy.15 In order to overcome this deficiency, ordered bulk heterojunction (OBHJ) structure was introduced in which ZnO or TiOx nanowire (NW) arrays electrodes are infiltrated with CQDs.16-19 This interpenetrating structure allows the film thickness to reach into several micrometers and at the same time, ensures efficient charge extraction.20 Tremendous efforts have been made to raise the PCEs of CQD solar cells based on OBHJ structure through band alignment engineering,19 surface passivation16 and size tailoring of the ordered electrode substrate.21 However, the development of CQDs OBHJ solar cells still lags far behind that of the planar structure. The low performance of CQDs OBHJ solar cells demonstrated so far can be mainly traced to the limited FF and high Voc deficit which are partially contributed to the unfavorable infiltration of CQDs into nanorods interspace and inherent defects on large electrodes surfaces.17,

22

Surface passivation and self-assembled monolayers (SAMs)

modification of electrodes have been extensively employed to CQDs and organic solar cells based on both OBHJ and planar structure, leaving clear outlines for further 3



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reference.23-25 However, despite the early clarification of the interfacial morphology deficiency based on CQDs OBHJ solar cells,17 few attentions have been paid on technological improvement, which we thought to be a major potential breakpoint for further improving the efficiency of CQDs OBHJ solar cells. Convective assembly is one of the commonly used meniscus-guided coating (MGC) techniques, where the CQDs can be slowly guided by a meniscus during deposition process.26 The strong attractive interaction between CQDs and electrodes substrate may force dense packing and facilitate infiltration of CQDs.27-30 This inherent directionality accompanied with nearly 99 % utilization ratio of active materials and compatibility with flexible and scalable manufacturing process make convective assembly an ideal deposition technique for the construction of CQDs OBHJ solar cells. The similar MGC method of doctor blading has been introduced in planar structure CQD solar cells, demonstrating promising application of MGC in achieving high efficiency and scalable fabrication of CQD solar cells.31-32 In this work, morphological deficiency of CQD OBHJ solar cells based on ZnO NW arrays was overcome through controlling the growth orientation of ZnO NWs and substitution of the lab-scale spin coating method with scalable convective assembly. The influences of both the orientations of NWs and deposition techniques on interfacial morphology, device performance and charge carrier kinetic process were systematically studied. Benefitting from the strong capillary interaction between CQDs and ZnO NW arrays, convective assembly led to a much better infiltration of CQDs into the ZnO NWs interspace, constructing a fine interpenetration OBHJ structure and thus facilitating the light harvesting and charge collection in solar cells. Besides, 4-aminobenzoic acid (ABA) was induced as a self-assembled monolayer to improve the Voc deficit caused by the inherent defects on ZnO NWs grown through low-temperature hydrothermal method. As a result, the best cell combined with convective assembly deposition methods and surface modification of vertical-aligned ZnO NW arrays showed a PCE of 9.92%, which, to the best of our knowledge, is the best PCE of CQD solar cells based on OBHJ structure. 4


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morphology, we then discuss the effect of deposition method on morphological variations of OBHJ structure developed by CQDs and vertical-aligned ZnO NW arrays. The scalable convective assembly (CA) deposition technique was carried out as a comparison of the lab-scale spin coating method. The illustration of the process for the convective assembly of CQD film is shown in Figure 2a. During the assembly process, the evaporative flow related to the coffee-ring effect brings CQDs toward the contact line at first. The CQDs are subsequently drawn into a thin film along with the forming of localized liquid bridges that could bring strong dot-to-dot and dot-to-substrate capillary attractions. These interactions coupled with strong evaporation pressure may facilitate the infiltration of CQDs into the interspaces between ZnO NWs. In particular, the surface morphology of CQDs prepared through spin coating and convective assembly varied remarkably at the first few deposited layers (See SEM images in Figure S5). These variations draw our attention to the significance of interfacial morphology between ZnO NWs and CQDs. Electron microscopic studies were used to reveal and understand the capillary effect introduced by convective assembly. To preserve the interfacial details as much as possible, focused ion beam (FIB) was applied for the preparation of cross-section slide of CQD solar cells. Figure 2b, c indicate cross-section images of CQD devices obtained by FIB-TEM. The device structure and the vertical morphology of each functional layer can be clearly observed. Since ZnO has a lower density than PbS CQDs, the change of interfacial condition can be captured by a clear mass-thickness contrast variation in bright-field TEM images. Evidently, through changing the deposition method, both the bulk morphology of CQD layers and interfacial morphology between CQDs and ZnO NW arrays evolve visibly. The layer-by-layer spin-coated CQD film shows clear horizontal stripes between each layer as shown in Figure 2b, which may inhibit the carrier transport in CQD films and device performance as suggested in Figure S7.36 More importantly, the intact ZnO in magnified TEM images around the CQDs/ZnO NWs interface infer spatial separation between PbS CQDs and ZnO NWs, suggesting unsuccessful CQDs infiltration. In contrast, the convective assembled devices exhibit 7




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ZnO NWs fabricated through spin-coating or convective assembly; (b) dark J-V curves of devices prepared through different conditions; (c) light-intensity dependent of Voc of devices with different configurations (solid lines: linear fits); (d) electrochemical impedance spectroscopy (EIS) of devices prepared under different conditions. After clarifying the effect of ZnO NWs growth orientation and deposition technique on interfacial morphology, PbS CQD OBHJ solar cells were fabricated with various conditions. A length of approximately 150-200 nm for the ZnO nanorod arrays and a thickness of 250 nm for CQDs active layer were demonstrated as the optimized configurations for iodide-capped CQDs OBHJ.19 The CQDs used in OBHJ devices show a rock salt structure with an optical bandgap of 1.26 eV and a diameter of ~3 nm, as shown in Figure S8. Notably, the whole fabrication process of these convective assembled CQD OBHJ solar cells based on vertically aligned ZnO NW arrays was carried out with a maximum annealing temperature of 150 °C (80 °C for CQDs and 150 °C for ZnO) which is compatible with flexible substrate and fast manufacturing process such as roll-to-roll production. The J-V curves are plotted in Figure 3a, with the corresponding detailed photovoltaic parameters summarized in Table 1. The devices fabricated on NW arrays with random orientations through CA show an average PCE of only 7.65%. Similarly, unfavorable device performance with a poor FF of 0.55 was obtained for CQD devices prepared through spin coating on vertically aligned ZnO NWs, resulting in an average PCE of 7.62%. These deficiencies in efficiency show that the device performance is seriously limited by the incomplete CQDs infiltrations as clarified above. As for the devices constructed on the vertically aligned ZnO NW arrays through convective assembly, a significant improvement of overall device performance was observed, especially for the FF, with an average PCE of 8.41%, an FF of 0.60, Voc of 0.51 V and Jsc of 27.4 mA cm-2. The EQE spectra of OBHJ devices have been measured as shown in Figure S9. The integral current densities are close to the Jsc measured by solar simulator within a reasonable deviation of 5%. We observed that the CA device shows superior EQE in 9



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the near-infrared region, indicating increased effective CQD film thickness due to improved infiltration of CQDs inside the interspace of ZnO NWs,

10, 16

which is in

accordance with the absorbance spectra and TEM images in Figure S8d and Figure 2, respectively. Besides, the suppression of trap-assisted charge carrier recombination in solar cells can be inferred by the change of the ideality factor of solar cells both under dark and light illumination conditions as shown in Figure 3b, c.37 The calculated light ideality factors nL of convective assembled devices are in accordance with the trend of dark ideal factors nD. The convective assembly leads to the uniform film morphology and the elimination of interfacial voids which could improve CQDs/ZnO contact and increase the effective thickness of CQD absorbers, realizing efficient CQD OBHJ solar cells.

Table.1. Photovoltaic parameters of CQD devices based on ZnO NWs with different conditions. Voc

Jsc

Jsc,EQEa

FF

PCEb

[V]

[mA·cm-2]

[mA·cm-2]

[%]

[%]

Vertical

0.50±0.01

27.3±0.67

27.1

55.4±2.7

7.62±0.53

Random

0.49±0.01

26.6±0.92

26.2

58.7±3.1

7.65±0.42

Vertical

0.51±0.01

27.4±0.71

27.3

60.0±2.2

8.41±0.22

Vertical +ABA

0.54±0.01

27.5±0.99

27.7

64.0±1.5

9.52±0.35

Deposition Method

ZnO NWs

Spin

CA

aThe

Jsc,EQE represents the integrated current density obtained from EQE spectra. The

average device parameters were calculated form 12 paralleled devices.

In order to gain insights into the electrical properties of our CQD OBHJ solar cells, electrochemical impedance spectroscopy (EIS) was performed to analyze electron transport kinetic in our working cells. Figure 3d shows the Nyquist plot measured at open circuit condition under light illumination with a frequency range from 0.05 Hz to 250 kHz. A widely used equivalent circuit model is employed to fit 10


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the Nyquist plot.38-40 The fitting results of EIS parameters obtained from different devices are listed in Table S1. Convective assembled devices constructed on ZnO NW arrays create a lower charge transport resistance (Rtr) and a higher order of magnitude for geometry capacity (Cgeo) compared with that of spin-coated devices, implying better charge transport in CQDs active layers due to striations-free morphology and improved interfacial contact. The significantly reduced charge transfer resistance (Rct) and prolonged lifetime

oc

( oc= RctCµ) obtained from devices

assembled on vertical-aligned ZnO NW arrays suggest preferable charge transfer and extraction behavior at ZnO NWs and CQDs interfaces, which are consistent with the aforementioned ideality factor results and morphology observations.

(a)

(b)

Figure 4. (a) Light intensity dependent transport and recombination lifetime constants for OBHJ devices based on vertical or random NWs, deposited by spin-coating or CA techniques; (b) Charge collection efficiency as a function of the incident light intensity. 11



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In addition, intensity modulated photocurrent and photovoltage spectroscopy (IMVS/IMPS) were used to investigate the charge collection of CQD devices.41 The obtained effective electron transport time ( t) and electronic recombination lifetime ( n) as a function of light intensity are shown in Figure 4a. The relative Bode plots of different time constants are illustrated in Figure S10. Apparently, convective assembly generates a significantly higher

n calculated

from IMVS measurement when

compared with spin coating. Moreover, through combining convective assembly and vertically aligned ZnO NWs arrays, solar cells demonstrate the longest

n

under

different light intensity, indicating a slow charge recombination process rendered by evidently improved bulk and interfacial morphology. Surprisingly, the result of t from IMPS measurements was observed to be insensitive to light intensity. This light intensity independent feature indicates that the effective transport of charge carriers in our CQD OBHJ solar cells may be dominated by free carrier diffusion or drifting process rather than the trapping/detrapping processes.42-44 The trend of these time constants infers the decay of electron collection efficiency ( c) with increased light intensity as shown in Figure 4b. The convective assembled devices constructed on vertically aligned ZnO NW arrays show overall superior charge collection efficiency which proves the suppressing of charge carrier loss and effectiveness of charge extraction in convective assembled devices based on finely interpenetrating OBHJ structure.

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introduced by ABA modification which effectively raises the vacuum level. Thereafter, the Fermi level difference between ZnO and PbS CQDs can be widened, resulting in improvement in Voc. The X-ray photoelectron spectroscopy (XPS) spectra clearly suggest the presence of ABA on ZnO NWs surfaces after modification and washing steps as shown in Figure 5b. The shift of vacuum level of ZnO NWs is also clarified through ultraviolet photoelectron spectroscopy (UPS) in Figure 5c. As for the CQD OBHJ solar cells, after careful optimizations (see Table S2), a notable increase in Voc was observed coupled with an enhancement in FF. The ideality factor of ABA-modified devices both under dark and illumination conditions reduced significantly. Meantime, the lowest Rct and longest

oc

value modulated from EIS

spectra shown in Figure 3d suggest a better charge extraction behavior. The introduction of ABA SAMs layer can not only optimize the interface energy level alignment between CQD and ZnO NWs, but also effectively suppress the interface recombination, as suggested by the dimmed defects-induced emission of ZnO NWs as shown in Figure S11 and the change of ideality factor as well as

oc

in Figure 3.45-46

Consequently, the highest PCE of 9.92% with a Voc of 0.55, a Jsc of 27.9 and an FF of 64.7% was obtained, which is the best performances so far for CQDs based OBHJ devices. In conclusion, we have clearly identified the poor interfacial morphology of conventional CQD OBHJ solar cells based on disordered ZnO NWs and lab-scale spin coating process, which seriously inhibits the charge carrier extraction and device performance. In order to improve interfacial morphology, vertical-aligned ZnO NW arrays and convective assembly technique were introduced together in the fabrication of CQD OBHJ solar cells. The capillary attractive interactions between CQDs and well-aligned ZnO NWs substrate during assembly process lead to dense packing and more efficient infiltration of CQDs, forming highly efficient OBHJ structures. Moreover, the Voc deficit can be effectively compensated by the introducing of ABA self-assembled monolayer on the surface of ZnO NW arrays, leading to the highest efficiency of 9.92%. We believe that improved interfacial morphology in OBHJ 14


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structure may also be achieved for others solution-processed photovoltaic materials such as polymers or perovskite by utilizing the synergetic effect of convective assembly and vertically aligned ZnO NWs. Moreover, the low-temperature deposition process of convective assembly is compatible with flexible and large-area mass manufacturing techniques. Thus our results may provide an innovative and general approach to construct OBHJ solar cells, which may also set a new stage for the future scalable production of OBHJ photovoltaic devices. ASSOCIATED CONTENT Experimental details on materials synthesis, device fabrication and measurements are shown in Supporting Information. The Supporting Information is available free of charge on the ACS Publications website.

AUTHOR INFORMATION Corresponding Author Email: [email protected]; [email protected]. Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This work was supported by the National Key Research Projects (Grant No.2016YFA0202402), the Natural Science Foundation of Jiangsu Province of China (BK20170337), the National Natural Science Foundation of China (Grant No. 61674111), the “111” projects and China Scholarship Council (CSC). The author thanks the Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University. We also acknowledge the Priority Academic Program Development of Jiangsu Higher Education Institution (PAPD) and Japan Society for the Promotion of Science (JSPS KAKENHI, Grant Number JP17H035036).

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REFERENCES (1) Yuan, M.; Liu, M.; Sargent, E. H., Colloidal Quantum Dot Solids for Solution-Processed Solar Cells. Nat. Energy 2016, 1, 16016. (2) Talapin, D. V.; Lee, J. S.; Kovalenko, M. V.; Shevchenko, E. V., Prospects of Colloidal Nanocrystals for Electronic and Optoelectronic Applications. Chem. Rev. 2010, 110, 389-458. (3) Rogach, A. L.; Klar, T. A.; Lupton, J. M.; Meijerink, A.; Feldmann, J., Energy Transfer with Semiconductor Nanocrystals. J. Mater. Chem. 2009, 19, 1208-1221. (4) Kramer, I. J.; Sargent, E. H., Colloidal Quantum Dot Photovoltaics: A Path Forward. ACS Nano 2011, 5, 8506-8514. (5) Shi, G.; Wang, Y.; Liu, Z.; Han, L.; Liu, J.; Wang, Y.; Lu, K.; Chen, S.; Ling, X.; Li, Y., et al., Stable and Highly Efficient PbS Quantum Dot Tandem Solar Cells Employing a Rationally Designed Recombination Layer. Adv. Energy Mater. 2017, 7, 1602667. (6) Wang, X.; Koleilat, G. I.; Tang, J.; Liu, H.; Kramer, I. J.; Debnath, R.; Brzozowski, L.; Barkhouse, D. A. R.; Levina, L.; Hoogland, S., et al., Tandem Colloidal Quantum Dot Solar Cells Employing a Graded Recombination Layer. Nat. Photon. 2011, 5, 480-484. (7) Ip, A. H.; Thon, S. M.; Hoogland, S.; Voznyy, O.; Zhitomirsky, D.; Debnath, R.; Levina, L.; Rollny, L. R.; Carey, G. H.; Fischer, A., et al., Hybrid Passivated Colloidal Quantum Dot Solids. Nat. Nanotechnol. 2012, 7, 577-582. (8) Wang, Y.; Lu, K.; Han, L.; Liu, Z.; Shi, G.; Fang, H.; Chen, S.; Wu, T.; Yang, F.; Gu, M., et al., In Situ Passivation for Efficient PbS Quantum Dot Solar Cells by Precursor Engineering. Adv. Mater. 2018, 30, 1704871. (9) Lu, K.; Wang, Y.; Liu, Z.; Han, L.; Shi, G.; Fang, H.; Chen, J.; Ye, X.; Chen, S.; Yang, F., et al., High-Efficiency PbS Quantum-Dot Solar Cells with Greatly Simplified Fabrication Processing via "Solvent-Curing". Adv. Mater. 2018, 30, 1707572. (10) Xu, J.; Voznyy, O.; Liu, M.; Kirmani, A. R.; Walters, G.; Munir, R.; Abdelsamie, M.; Proppe, A. H.; Sarkar, A.; Garcia de Arquer, F. P., et al., 2D Matrix Engineering for Homogeneous Quantum Dot Coupling in Photovoltaic Solids. Nat. Nanotechnol. 2018, 13, 456-462. (11) Beard, M. C.; Luther, J. M.; Semonin, O. E.; Nozik, A. J., Third Generation Photovoltaics Based on Multiple Exciton Generation in Quantum Confined Semiconductors. Acc. Chem. Res. 2013, 46, 1252-1260. (12) Zhitomirsky, D.; Voznyy, O.; Levina, L.; Hoogland, S.; Kemp, K. W.; Ip, A. H.; Thon, S. M.; Sargent, E. H., Engineering Colloidal Quantum Dot Solids within and Beyond the Mobility-Invariant Regime. Nat. Commun. 2014, 5, 3803. (13) Proppe, A. H.; Xu, J.; Sabatini, R. P.; Fan, J. Z.; Sun, B.; Hoogland, S.; Kelley, S. O.; Voznyy, O.; Sargent, E. H., Picosecond Charge Transfer and Long Carrier Diffusion Lengths in Colloidal Quantum Dot Solids. Nano Lett. 2018, 18, 7052-7059. 16


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(14) Zhitomirsky, D.; Voznyy, O.; Levina, L.; Hoogland, S.; Kemp, K. W.; Ip, A. H.; Thon, S. M.; Sargent, E. H., Engineering Colloidal Quantum Dot Solids within and Beyond the Mobility-Invariant Regime. Nat. Conmun. 2014, 5, 3803. (15) Lan, X.; Masala, S.; Sargent, E. H., Charge-Extraction Strategies for Colloidal Quantum Dot Photovoltaics. Nat. Mater. 2014, 13, 233-240. (16) Cheng, J. J.; Chuang, C.-H. M.; Hentz, O.; Rekemeyer, P. H.; Bawendi, M. G.; ! Z $ S., Dimension- and Surface-Tailored ZnO Nanowires Enhance Charge Collection in Quantum Dot Photovoltaic Devices. ACS Appl. Energy Mater. 2018, 1, 1815-1822. (17) Jean, J.; Chang, S.; Brown, P. R.; Cheng, J. J.; Rekemeyer, P. H.; Bawendi, M. G.; Gradecak, S.; Bulovic, V., ZnO Nanowire Arrays for Enhanced Photocurrent in PbS Quantum Dot Solar Cells. Adv. Mater. 2013, 25, 2790-2796. (18) Kramer, I. J.; Zhitomirsky, D.; Bass, J. D.; Rice, P. M.; Topuria, T.; Krupp, L.; Thon, S. M.; Ip, A. H.; Debnath, R.; Kim, H. C., et al., Ordered Nanopillar Structured Electrodes for Depleted Bulk Heterojunction Colloidal Quantum Dot Solar Cells. Adv. Mater. 2012, 24, 2315-2319. (19) Rekemeyer, P. H.; Chang, S.; Chuang, C.-H. M.; Hwang, G. W.; Bawendi, M. G.; ! Z $ S., Enhanced Photocurrent in PbS Quantum Dot Photovoltaics via ZnO Nanowires and Band Alignment Engineering. Adv. Energy Mater. 2016, 1600848. (20) Wang, H.; Kubo, T.; Nakazaki, J.; Kinoshita, T.; Segawa, H., PbS-Quantum-Dot-Based Heterojunction Solar Cells Utilizing ZnO Nanowires for High External Quantum Efficiency in the near-Infrared Region. J. Phys. Chem. Lett. 2013, 4, 2455-2460. (21) Wang, H.; Gonzalez-Pedro, V.; Kubo, T.; Fabregat-Santiago, F.; Bisquert, J.; Sanehira, Y.; Nakazaki, J.; Segawa, H., Enhanced Carrier Transport Distance in Colloidal PbS Quantum-Dot-Based Solar Cells Using ZnO Nanowires. J. Phys.Chem.C 2015, 119, 27265-27274. (22) Tam, K. H.; Cheung, C. K.; Leung, Y. H.; Djurisic, A. B.; Ling, C. C.; Beling, C. D.; Fung, S.; Kwok, W. M.; Chan, W. K.; Phillips, D. L., et al., Defects in ZnO Nanorods Prepared by a Hydrothermal Method. J. Phys. Chem. B 2006, 110, 20865-20871. (23) Kim, G. H.; Garcia de Arquer, F. P.; Yoon, Y. J.; Lan, X.; Liu, M.; Voznyy, O.; Jagadamma, L. K.; Abbas, A. S.; Yang, Z.; Fan, F., et al., High-Efficiency Colloidal Quantum Dot Photovoltaics via Robust Self-Assembled Monolayers. Nano Lett. 2015, 15, 7691-7696. (24) Ruankham, P.; Yoshikawa, S.; Sagawa, T., Water-Processed Self-Assembles of Monolayers as Interface Modifier for ZnO/P3HT Hybrid Solar Cells. Mater.Chem. Phys. 2013, 141, 278-282. (25) Chang, J.; Kuga, Y.; Mora-Sero, I.; Toyoda, T.; Ogomi, Y.; Hayase, S.; Bisquert, J.; Shen, Q., High Reduction of Interfacial Charge Recombination in Colloidal Quantum Dot Solar Cells by Metal Oxide Surface Passivation. Nanoscale 2015, 7, 5446-5456. (26) Muangnapoh, T.; Weldon, A. L.; Gilchrist, J. F., Enhanced Colloidal Monolayer 17



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Assembly via Vibration-Assisted Convective Deposition. Appl. Phys. Lett. 2013, 103, 181603. Kumnorkaew, P.; Ee, Y. K.; Tansu, N.; Gilchrist, J. F., Investigation of the Deposition of Microsphere Monolayers for Fabrication of Microlens Arrays. Langmuir 2008, 24, 12150-12157. Barako, M. T.; Sood, A.; Zhang, C.; Wang, J.; Kodama, T.; Asheghi, M.; Zheng, X.; Braun, P. V.; Goodson, K. E., Quasi-Ballistic Electronic Thermal Conduction in Metal Inverse Opals. Nano letters 2016, 16, 2754-2761. Dziomkina, N. V.; Vancso, G. J., Colloidal Crystal Assembly on Topologically Patterned Templates. Soft Matter 2005, 1, 265. Gu, X.; Shaw, L.; Gu, K.; Toney, M. F.; Bao, Z., The Meniscus-Guided Deposition of Semiconducting Polymers. Nat. Commun. 2018, 9, 534. Kirmani, A. R.; Sheikh, A. D.; Niazi, M. R.; Haque, M. A.; Liu, M.; de Arquer, F. P. G.; Xu, J.; Sun, B.; Voznyy, O.; Gasparini, N., et al., Overcoming the Ambient Manufacturability-Scalability-Performance Bottleneck in Colloidal Quantum Dot Photovoltaics. Adv. Mater. 2018, 30, 1801661. Aqoma, H.; Jang, S.-Y., Solid-State-Ligand-Exchange Free Quantum Dot Ink-Based Solar Cells with an Efficiency of 10.9%. Energy Environ. Sci.2018, 11, 1603-1609. Greene, L. E.; Law, M.; Tan, D. H.; Montano, M.; Goldberger, J.; Somorjai, G.; Yang, P., General Route to Vertical ZnO Nanowire Arrays Using Textured ZnO Seeds. Nano Lett. 2005, 5, 1231-1236. Ruankham, P.; Sagawa, T.; Sakaguchi, H.; Yoshikawa, S., Vertically Aligned ZnO Nanorods Doped with Lithium for Polymer Solar Cells: Defect Related Photovoltaic Properties. J. Mater. Chem. 2011, 21, 9710-9715. Lord, A. M.; Maffeis, T. G.; Walton, A. S.; Kepaptsoglou, D. M.; Ramasse, Q. M.; Ward, M. B.; Koble, J.; Wilks, S. P., Factors That Determine and Limit the Resistivity of High-Quality Individual ZnO Nanowires. Nanotechnology 2013, 24, 435706. Kramer, I. J.; Minor, J. C.; Moreno-Bautista, G.; Rollny, L.; Kanjanaboos, P.; Kopilovic, D.; Thon, S. M.; Carey, G. H.; Chou, K. W.; Zhitomirsky, D., et al., Efficient Spray-Coated Colloidal Quantum Dot Solar Cells. Adv. Mater. 2015, 27, 116-121. Panthani, M. G.; Kurley, J. M.; Crisp, R.; Dietz, T. C.; Ezzyat, T.; Luther, J. M.; Talapin, D. V., High Efficiency Solution Processed Sintered CdTe Nanocrystal Solar Cells: The Role of Interfaces. Nano Lett. 2014, 14, 670-675. Kwon, H. C.; Yang, W.; Lee, D.; Ahn, J.; Lee, E.; Ma, S.; Kim, K.; Yun, S. C.; Moon, J., Investigating Recombination and Charge Carrier Dynamics in a One-Dimensional Nanopillared Perovskite Absorber. ACS Nano 2018, 12, 4233-4245. Bai, Y.; Dong, Q.; Shao, Y.; Deng, Y.; Wang, Q.; Shen, L.; Wang, D.; Wei, W.; Huang, J., Enhancing Stability and Efficiency of Perovskite Solar Cells with Crosslinkable Silane-Functionalized and Doped Fullerene. Nat. Commun. 2016, 7, 12806. 18


Page 19 of 19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

(40) Shao, Y.; Xiao, Z.; Bi, C.; Yuan, Y.; Huang, J., Origin and Elimination of Photocurrent Hysteresis by Fullerene Passivation in CH3NH3PbI3 Planar Heterojunction Solar Cells. Nat. Commun. 2014, 5, 5784. (41) Zhu, K.; Neale, N. R.; Miedaner, A.; Frank, A. J., Enhanced Charge-Collection Efficiencies and Light Scattering in Dye-Sensitized Solar Cells Using Oriented TiO2 Nanotubes Arrays. Nano Lett. 2007, 7, 69-74. (42) Cao, F.; Oskam, G.; Meyer, G. J.; Searson, P. C., Electron Transport in Porous Nanocrystalline TiO2 Photoelectrochemical Cells. J. Phys. Chem. 1996, 100, 17021-17027. (43) Oekermann, T.; Yoshida, T.; Minoura, H.; Wijayantha, K. G. U.; Peter, L. M., Electron Transport and Back Reaction in Electrochemically Self-Assembled Nanoporous ZnO/Dye Hybrid Films. J. Phys. Chem. B 2004, 108, 8364-8370. (44) Sung, Y.-H.; Liao, W.-P.; Chen, D.-W.; Wu, C.-T.; Chang, G.-J.; Wu, J.-J., Room-Temperature Tailoring of Vertical ZnO Nanoarchitecture Morphology for Efficient Hybrid Polymer Solar Cells. Adv. Funct. Mater. 2012, 22, 3808-3814. (45) Sivashanmugan, K.; Lin, C.-H.; Hsu, S.-H.; Guo, T.-F.; Wen, T.-C., Interfacial Engineering of ZnO Surface Modified with Poly-vinylpyrrolidone and P-aminobenzoic Acid for High-Performance Perovskite Solar Cells. Mater. Chem. Phys. 2018, 219, 90-95. (46) Yan, D.; Zhang, W.; Cen, J.; Stavitski, E.; Sadowski, J. T.; Vescovo, E.; Walter, A.; Attenkofer, K.; Stacchiola, D. J.; Liu, M., Near Band Edge Photoluminescence of ZnO Nanowires: Optimization via Surface Engineering. Appl. Phys. Lett. 2017, 111, 231901.

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Finely Interpenetrating Bulk Heterojunction Structure for Lead Sulfide

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