{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,6]],"date-time":"2025-12-06T17:12:06Z","timestamp":1765041126576,"version":"build-2065373602"},"reference-count":50,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2020,11,17]],"date-time":"2020-11-17T00:00:00Z","timestamp":1605571200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"The National Research Foundation of Korea(NRF) grant funded by the Korea government(MSIT)","award":["2017R1A2A2A05069821"],"award-info":[{"award-number":["2017R1A2A2A05069821"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>In this paper, we studied the optimized conditions for adding inorganic quantum dots (QD) to the P3HT:PC70BM organic active layer to increase the sensitivity of the indirect X-ray detector. Commonly used QDs are composed of hazardous substances with environmental problems, so indium phosphide (InP) QDs were selected as the electron acceptor in this experiment. Among the three different sizes of InP QDs (4, 8, and 12 nm in diameter), the detector with 4 nm InP QDs showed the highest sensitivity, of 2.01 mA\/Gy\u00b7cm2. To further improve the sensitivity, the QDs were fixed to 4 nm in diameter and then the amount of QDs added to the organic active layer was changed from 0 to 5 mg. The highest sensitivity, of 2.26 mA\/Gy\u00b7cm2, was obtained from the detector with a P3HT:PC70BM:InP QDs (1 mg) active layer. In addition, the highest mobility, of 1.69 \u00d7 10\u22125 cm2\/V\u00b7s, was obtained from the same detector. Compared to the detector with the pristine P3HT:PC70BM active layer, the detector with a P3HT:PC70BM:InP QDs (1 mg) active layer had sensitivity that was 61.87% higher. The cut-off frequency of the P3HT:PC70BM detector was 21.54 kHz, and that of the P3HT:PC70BM:InP QDs (1 mg) detector was 26.33 kHz, which was improved by 22.24%.<\/jats:p>","DOI":"10.3390\/s20226562","type":"journal-article","created":{"date-parts":[[2020,11,17]],"date-time":"2020-11-17T07:23:28Z","timestamp":1605597808000},"page":"6562","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["A Study on an Organic Semiconductor-Based Indirect X-ray Detector with Cd-Free QDs for Sensitivity Improvement"],"prefix":"10.3390","volume":"20","author":[{"given":"Jehoon","family":"Lee","sequence":"first","affiliation":[{"name":"Department of Electronic and Electrical Engineering, Dankook University, Gyeonggi-do 16890, Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6070-2897","authenticated-orcid":false,"given":"Hailiang","family":"Liu","sequence":"additional","affiliation":[{"name":"Department of Electronic and Electrical Engineering, Dankook University, Gyeonggi-do 16890, Korea"}]},{"given":"Jungwon","family":"Kang","sequence":"additional","affiliation":[{"name":"Department of Electronic and Electrical Engineering, Dankook University, Gyeonggi-do 16890, Korea"}]}],"member":"1968","published-online":{"date-parts":[[2020,11,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1016\/j.nantod.2018.12.002","article-title":"Colloidal nanocrystals for heterogeneous catalysis","volume":"24","author":"Losch","year":"2019","journal-title":"Nano Today"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"10934","DOI":"10.1021\/acs.chemrev.6b00164","article-title":"Two-Dimensional Colloidal Nanocrystals","volume":"116","author":"Nasilowski","year":"2016","journal-title":"Chem. Rev."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"e1602916","DOI":"10.1126\/sciadv.1602916","article-title":"Pressure compression of CdSe nanoparticles into luminescent nanowires","volume":"3","author":"Li","year":"2017","journal-title":"Sci. Adv."},{"key":"ref_4","first-page":"11220","article-title":"Self-Assembly of Colloidal Nanocrystals: From Intricate Structures to Functional Materials","volume":"116","author":"Boles","year":"2016","journal-title":"Sci. Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"271","DOI":"10.1038\/s41467-019-14014-3","article-title":"Optically pumped colloidal-quantum-dot lasing in LED-like devices with an integrated optical cavity","volume":"11","author":"Roh","year":"2020","journal-title":"Nat. Commun."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"5116","DOI":"10.1021\/acs.chemmater.9b01010","article-title":"One Stone, Two Birds High-Efficiency Blue-Emitting Perovskite Nanocrystals for LED and Security Ink Applications","volume":"31","author":"Sun","year":"2019","journal-title":"Chem. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1016\/j.jechem.2019.12.022","article-title":"Strategies for enhancing conductivity of colloidal nanocrystals and their photoelectronic applications","volume":"48","author":"Qiao","year":"2020","journal-title":"J. Energy Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"6590","DOI":"10.1021\/acs.jpclett.9b02605","article-title":"CsPbBr3 Perovskite Nanocrystal Grown on MXene Nanosheets for Enhanced Photoelectric Detection and Photocatalytic CO2 Reduction","volume":"10","author":"Pan","year":"2019","journal-title":"J. Phys. Chem. Lett."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"25154","DOI":"10.1021\/acsami.8b07859","article-title":"General and Scalable Approach to Bright, Stable, and Functional AIE Fluorogen Colloidal Nanocrystals for in Vivo Imaging","volume":"10","author":"Yan","year":"2018","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"550","DOI":"10.1039\/C7TB02912H","article-title":"Stable DHLA\u2013PEG capped PbS quantum dots: From synthesis to near-infrared biomedical imaging","volume":"6","author":"Zamberlan","year":"2018","journal-title":"J. Mater. Chem. B"},{"key":"ref_11","first-page":"P10015","article-title":"Ultrafast emission from colloidal nanocrystals under pulsed X-ray excitation","volume":"11","author":"Turtos","year":"2016","journal-title":"J. Intrum."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"190501","DOI":"10.1063\/1.5125999","article-title":"A perspective on the bright future of metal halide perovskites for X-ray detection","volume":"115","author":"Sytnyk","year":"2019","journal-title":"Appl. Phys. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Kim, S., Lee, J., and Kang, J. (2020). Sensitivity Improvement of Quantum Dot-Blended Hybrid Detector for X-ray Imaging. Coatings, 10.","DOI":"10.3390\/coatings10030222"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2926","DOI":"10.1038\/s41467-018-05301-6","article-title":"High sensitivity organic inorganic hybrid X-ray detectors with direct transduction and broadband response","volume":"9","author":"Thirimanne","year":"2018","journal-title":"Nat. Commun."},{"key":"ref_15","first-page":"C01009","article-title":"Improving the sensitivity of indirect-type organic X-ray detector by blending with CdSe quantum dots","volume":"12","author":"Kim","year":"2016","journal-title":"J. Intrum."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.nima.2014.03.062","article-title":"Modifications in structural and electrical properties of gamma irradiated CdSe nanowire","volume":"753","author":"Kumari","year":"2014","journal-title":"Nucl. Instrum. Methods Phys. Res. A"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"37","DOI":"10.1038\/s41699-019-0120-8","article-title":"On the use of CdSe scintillating nanoplatelets as time taggers for high-energy gamma detection","volume":"3","author":"Turtos","year":"2019","journal-title":"NPJ 2D Mater. Appl."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"101","DOI":"10.4103\/1450-1147.203079","article-title":"Cadmium Telluride Semiconductor Detector for Improved Spatial and Energy Resolution Radioisotopic Imaging","volume":"16","author":"Abbaspour","year":"2017","journal-title":"World J. Nucl. Med."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"181914","DOI":"10.1063\/1.3589366","article-title":"CdTe quantum dots and polymer nanocomposites for X-ray scintillation and imaging","volume":"98","author":"Kang","year":"2011","journal-title":"Appl. Phys. Lett."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1016\/j.orgel.2016.03.023","article-title":"PbS quantum dot based hybrid-organic photodetectors for X-ray sensing","volume":"33","author":"Ankah","year":"2016","journal-title":"Org. Electron."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1901600","DOI":"10.1002\/admi.201901600","article-title":"Atomic Layer Deposition of ZnO on InP Quantum Dot Films for Charge Separation, Stabilization, and Solar Cell Formation","volume":"7","author":"Crisp","year":"2020","journal-title":"Adv. Mater. Interfaces"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"34","DOI":"10.1016\/S0168-9002(03)01545-6","article-title":"CaAs radiation imaging detectors with an active layer thickness up to 1 mm","volume":"509","author":"Tyazhev","year":"2003","journal-title":"Nucl. Instrum. Methods Phys. Res. A"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"183301","DOI":"10.1063\/1.4986345","article-title":"Dynamics of direct X-ray detection processes in High-Z Bi2O3 nanoparticles-loaded PFO polymer-based diodes","volume":"111","author":"Ciavatti","year":"2017","journal-title":"Appl. Phys. Lett."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"6973","DOI":"10.1021\/acsnano.9b01916","article-title":"Millimeter-Scale Unipolar Transport in High Sensitivity Organic-Inorganic Semiconductor X-ray Detectors","volume":"13","author":"Jayawardena","year":"2019","journal-title":"ACS Nano."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1801967","DOI":"10.1002\/advs.201801967","article-title":"Eco-Friendly Colloidal Quantum Dot-Based Luminescent Solar Cenecntrators","volume":"6","author":"You","year":"2019","journal-title":"Adv. Sci."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"736","DOI":"10.3389\/fphar.2018.00736","article-title":"Cytoxicity of InP\/ZnS Quantum Dots with Different Surface Functional Groups Toward Two Lung-Derived Cell Lines","volume":"9","author":"Chen","year":"2018","journal-title":"Front. Pharmacol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"9203","DOI":"10.1021\/ja504310w","article-title":"High-Efficiency \u201cGreen\u201d Quantum Dots Solar Cell","volume":"136","author":"Pan","year":"2014","journal-title":"J. Am. Chem. Soc."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"6569","DOI":"10.1021\/acsaem.8b01453","article-title":"Highly Photoconductive InP Quantum Dots Films and Solar Cells","volume":"1","author":"Crips","year":"2018","journal-title":"ACS Appl. Energy Mater."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2762","DOI":"10.1016\/j.orgel.2013.07.036","article-title":"Development of nanoimprinted InP QDs decorated polyaniline solar cell with conversion efficiency 3%","volume":"14","author":"Mahmoud","year":"2013","journal-title":"Org. Electron."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Ho, A.H.P., Kim, D., and Somekh, M.G. (2017). Cadmiun-Free Quantum Dots for Biophotonic Imaging and Sensing. Handbook of Photonics for Biomedical Engineering, Springer. [1st ed.].","DOI":"10.1007\/978-94-007-5052-4"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"C03008","DOI":"10.1088\/1748-0221\/14\/03\/C03008","article-title":"Characteristics of a Flexible Radiation Detector Fabricated with Non-Fullerene Acceptor for an Indirect-type X-ray Imaging","volume":"14","author":"Lee","year":"2019","journal-title":"J. Instrum."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"225502","DOI":"10.1063\/1.4999759","article-title":"Thin film organic photodetectors for indirect X-ray detection demonstrating low dose rate sensitivity at low voltage","volume":"122","author":"Starkenburg","year":"2017","journal-title":"J. Appl. Phys."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"13063","DOI":"10.1038\/ncomms13063","article-title":"Direct X-ray photoconversion in flexible organic thin film devices operated below 1 V","volume":"7","author":"Basirico","year":"2016","journal-title":"Nat. Commun."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"436","DOI":"10.1038\/nphoton.2017.94","article-title":"High-performance direct conversion X-ray detectors based on sintered hybrid lead triiodide perovskite wafers","volume":"11","author":"Cherstha","year":"2017","journal-title":"Nat. Photonics"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"10444","DOI":"10.1039\/C6TA02523D","article-title":"Photon energy transfer by quantum dots in organic-inorganic hybrid solar cells through FRET","volume":"4","author":"Han","year":"2016","journal-title":"J. Mater. Chem. A"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1800077","DOI":"10.1002\/solr.201800077","article-title":"Highly Efficient Ternary Solar Cells of 10.2% with Core\/Shell Quantum Dots via FRET Effect","volume":"2","author":"Han","year":"2018","journal-title":"Sol. RRL"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"26783","DOI":"10.1021\/acs.jpcc.5b09397","article-title":"Small-Size Effects on Electron Transfer in P3HT\/InP Quantum Dots","volume":"119","author":"Yin","year":"2015","journal-title":"J. Phys. Chem. C"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.1166\/nnl.2017.2459","article-title":"Comparative studies between photovoltaic and radiation parameters in indirect-type organic X-ray detector with a P3HT: PCBM active layer","volume":"9","author":"Lee","year":"2017","journal-title":"Nanosci. Nanotechnol. Lett."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"418","DOI":"10.1021\/acsenergylett.9b02450","article-title":"Chemi-Structural Stabilization of Formamidinium Lead Iodide Perovskite by Using Embedded Quantum Dots","volume":"5","author":"Masi","year":"2020","journal-title":"ACS Energy Lett."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"628","DOI":"10.1038\/nmat3655","article-title":"Microstructure formation in molecular and polymer semiconductors assisted by nucleation agents","volume":"12","author":"Treat","year":"2013","journal-title":"Nat. Mater."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"685","DOI":"10.1038\/44359","article-title":"Two-dimensional charge transport in self-organized, high-mobility conjugated polymers","volume":"401","author":"Sirringhaus","year":"1999","journal-title":"Nature"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"5714","DOI":"10.1039\/C6CS00942E","article-title":"Insights into charge carrier dynamics in organo-metal halide perovskites: From neat films to solar cells","volume":"46","author":"Peng","year":"2017","journal-title":"Chem. Soc. Rev."},{"key":"ref_43","unstructured":"Takeshita, S. (2008). Modeling of Space-Charge-Limited Current Injection Incorporating an Advanced Model of the Poole-Frenkel Effect. [Master\u2019s Thesis, Clemson University]."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"7426","DOI":"10.1063\/1.369373","article-title":"Numeric simulations of the electronical characteristics and the efficiencies of single-layer organic light emitting diodes","volume":"85","author":"Malliaras","year":"1999","journal-title":"J. Appl. Phys."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"1127","DOI":"10.1063\/1.112118","article-title":"Influence of effective-medium dielectric constant on electronic transport in an arylamine-containing glassy polymer","volume":"65","author":"Abkowitz","year":"1949","journal-title":"Appl. Phys. Lett."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"013706","DOI":"10.1063\/1.2158494","article-title":"Application of admittance spectroscopy to evaluate carrier mobility in organic charge transport materials","volume":"99","author":"Tsang","year":"2006","journal-title":"J. Appl. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"055018","DOI":"10.1063\/1.5087832","article-title":"Space-charge limited conduction in epitaxial chromia films grown on elemental and oxide-based metallic substrates","volume":"9","author":"Kwan","year":"2019","journal-title":"AIP Adv."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1007\/s11082-020-02362-0","article-title":"Dependence of mobility and charge injection on active layer thickness of bulk heterojunction organic solar cells: PCBM:P3HT","volume":"52","author":"Jhamba","year":"2020","journal-title":"Opt. Quantum Electron."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"759","DOI":"10.1039\/C9TC05695E","article-title":"Charge carrier traps in organic semiconductors: A review on the underlying physics and impact on electronic devices","volume":"8","author":"Haneef","year":"2020","journal-title":"J. Mater. Chem. C"},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"2375","DOI":"10.1063\/1.364276","article-title":"Effective dielectric constant of random composite materials","volume":"81","author":"Sareni","year":"1997","journal-title":"J. Appl. Phys."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6562\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:34:31Z","timestamp":1760178871000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/20\/22\/6562"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,11,17]]},"references-count":50,"journal-issue":{"issue":"22","published-online":{"date-parts":[[2020,11]]}},"alternative-id":["s20226562"],"URL":"https:\/\/doi.org\/10.3390\/s20226562","relation":{},"ISSN":["1424-8220"],"issn-type":[{"type":"electronic","value":"1424-8220"}],"subject":[],"published":{"date-parts":[[2020,11,17]]}}}