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Dive into the research topics where Dal Yong Lee is active.

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Featured researches published by Dal Yong Lee.


Journal of Materials Chemistry | 2014

Highly efficient imide functionalized pyrrolo[3,4-c]pyrrole-1,3-dione-based random copolymer containing thieno[3,4-c]pyrrole-4,6-dione and benzodithiophene for simple structured polymer solar cells

Vellaiappillai Tamilavan; Kyung Hwan Roh; Rajalingam Agneeswari; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun

As an effort to improve the photovoltaic properties of a highly efficient large band gap (2.11 eV) alternating copolymer, P(BDT-TDPPDT), comprised of electron rich benzodithiophene (BDT) and novel electron accepting pyrrole-based imide functionalized 4,6-bis(thiophen-2-yl)-2,5-dioctylpyrrolo[3,4-c]pyrrole-1,3-dione (TDPPDT) derivatives, we incorporated a relatively strong electron accepting thiophene-based imide functionalized thieno[3,4-c]pyrrole-4,6-dione (TPD) unit in its main chain via random copolymerization between BDT, TDPPDT and TPD units to give polymer P1. The incorporation of a TPD unit resulted in significant improvement in the optoelectrical and photovoltaic properties. P1 exhibits lower optical band gap (1.91 eV) and a deeper lowest unoccupied molecular orbital (LUMO) energy level compared to those of P(BDT-TDPPDT). The hole mobility of P1 was 3.66 × 10−4 cm2 V−1 s−1 and the PSC made with a simple device structure of ITO/PEDOT:PSS/P1:PC70BM(1 : 2.25 wt%) + 3 vol%/Al gave a maximum power conversion efficiency (PCE) of 7.03% with high photovoltaic parameters, such as an open-circuit voltage (Voc) of 0.87 V, a short-circuit current (Jsc) of 11.52 mA cm−2 and a fill factor (FF) of 70%. Interestingly, P1-based PSCs exhibited a high incident photon to current efficiency (IPCE) of a maximum of 78% at 410 nm and a more than 70% response between 370–590 nm. The PCE achieved in this study is the highest value reported thus far among PSCs made with random copolymers.


RSC Advances | 2015

Tuning the physical properties of pyrrolo[3,4-c]pyrrole-1,3-dione-based highly efficient large band gap polymers via the chemical modification on the polymer backbone for polymer solar cells

Vellaiappillai Tamilavan; Dal Yong Lee; Rajalingam Agneeswari; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun

A systematic modulation of the photo-physical properties of high energy converting large band gap (2.04 eV) alternating polymers (PBDTT–DPPD) containing electron rich 2D-conjugated benzodithiophene (BDTT) and weak electron accepting pyrrolo[3,4-c]pyrrole-1,3-dione (DPPD) derivatives via the incorporation of a relatively strong electron accepting thieno[3,4-c]pyrrole-4,6-dione (TPD), thieno[3,4-b]thiophene (TT), or pyrrolo[3,4-c]pyrrole-1,4-dione (DPP) unit on the polymer backbone was demonstrated. All three new random copolymers, RP1, RP2 and RP3, displayed broad absorption bands and lower optical band gaps compared to those of their parent alternating polymer, PBDTT–DPPD. The estimated band gaps of RP1, RP2 and RP3 decreased gradually from 2.04 eV for PBDTT–DPPD to 1.87 eV, 1.60 eV and 1.45 eV, respectively. The decrease in the band gaps of RP1, RP2 and RP3 was associated mainly with the alteration of their conduction bands. Interestingly, RP1 and RP2 showed slightly improved hole mobilities and RP3 exhibited one order lower hole mobility than that of PBDTT–DPPD. The estimated mobilities of RP1, RP2 and RP3 were 1.4 × 10−3 cm2 V−1 s−1, 3.7 × 10−3 cm2 V−1 s−1 and 4.9 × 10−4 cm2 V−1 s−1, respectively. The polymer solar cells (PSCs) prepared from RP1, RP2 or RP3 as donors and PC70BM as an acceptor using a simple device configuration of ITO/PEDOT:PSS/polymer:PC70BM + DIO/Al exhibited a maximum power conversion efficiency (PCE) of 5.35%, 5.05% and 2.41%, respectively.


New Journal of Chemistry | 2016

Effects of the incorporation of bithiophene instead of thiophene between the pyrrolo[3,4-c]pyrrole-1,3-dione units of a bis(pyrrolo[3,4-c]pyrrole-1,3-dione)-based polymer for polymer solar cells

Vellaiappillai Tamilavan; Seungmin Kim; Ji Yeong Sung; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Jung-Hyun Jeong; Sung Heum Park; Myung Ho Hyun

A new wide band gap polymer, P(BDTT–BTBDPPD), consisting of electron rich 4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene (BDTT) and electron deficient bithiophene-incorporated bis(pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) (BTBDPPD) derivative was prepared to improve the photovoltaic performances of a reported polymer, P(BDTT–TBDPPD), containing BDTT and thiophene-incorporated bis(pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) (TBDPPD) derivative. Polymer P(BDTT–BTBDPPD) exhibited maximum absorption at 478 nm and the calculated optical band gap was 2.10 eV. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P(BDTT–BTBDPPD) were estimated to be −5.44 eV and −3.34 eV. The hole mobility of P(BDTT–BTBDPPD) was 3.22 × 10−4 cm2 V−1 s−1. The polymer solar cells (PSCs) prepared using P(BDTT–BTBDPPD) : PC70BM (1 : 2 wt%) + 3 vol% DIO blend offered a maximum power conversion efficiency (PCE) of 4.62% with an open-circuit voltage (Voc) of 0.90 V, a short-circuit current (Jsc) of 7.99 mA cm−2, and a fill factor (FF) of 64%. This study suggests that the replacement of the thiophene spacer unit located between the pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione units of bis(pyrrolo[3,4-c]pyrrole-1,3(2H,5H)-dione) derivative with a bithiophene unit did not considerably alter the energy levels and charge transport properties of the resulting polymer. However, the overall photovoltaic performance was improved due mainly to the enhanced morphology of the photoactive layer.


New Journal of Chemistry | 2015

Modulation of the properties of pyrrolo[3,4-c]pyrrole-1,4-dione based polymers containing 2,5-di(2-thienyl)pyrrole derivatives with different substitutions on the pyrrole unit

Rajalingam Agneeswari; Insoo Shin; Vellaiappillai Tamilavan; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun

In this study, four new pyrrolo[3,4-c]pyrrole-1,4-dione (DKPP)-based polymers, P(DKPP-TPTH), P(DKPP-TPTE), P(DKPP-TPTA), and P(DKPP-TPTI), containing N-alkyl-2,5-di(2-thienyl)pyrrole (TPT) derivatives with four different substituents such as hydrogen, ester, amide, and imide groups on the 3,4-position of the pyrrole unit were prepared to tune the properties of the polymers. Opto-electrical studies showed that the incorporation of electron withdrawing substituents such as ester, amide and imide groups instead of hydrogen into the pyrrole backbone of the polymers increased the band gaps significantly from 1.31 eV to 1.42 eV, 1.37 eV and 1.37 eV, respectively, and reduced the highest occupied/lowest unoccupied molecular orbital (HOMO/LUMO) energy levels from −4.96 eV/−3.65 eV to −5.24 eV/−3.82 eV, −5.17 eV/−3.80 eV and −5.35 eV/−3.98 eV, respectively. Organic field effect transistors (OFETs) made from these polymers indicated that the incorporation of electron withdrawing functional groups into the polymer backbone reduced hole mobility. Polymer solar cells (PSCs) prepared using polymers as electron donors offered higher power conversion efficiency (PCE) for the polymer containing hydrogen on the TPT backbone, but the polymers incorporating electron withdrawing substituents into the TPT backbone showed a significantly higher open-circuit voltage (Voc) though the PCE was relatively low.


New Journal of Chemistry | 2018

Pyrrole N-alkyl side chain effects on the properties of pyrrolo[3,4-c]pyrrole-1,3-dione-based polymers for polymer solar cells

Vellaiappillai Tamilavan; Jihoon Lee; Dal Yong Lee; Rajalingam Agneeswari; Yun Kyung Jung; Youngeup Jin; Jung Hyun Jeong; Myung Ho Hyun; Sung Heum Park

In this study, two new pyrrolo[3,4-c]pyrrole-1,3-dione (PPD)-based polymers (P3 and P4) incorporating a 2-octyldodecyl (branched alkyl) group on the pyrrole nitrogen of the PPD unit were prepared. Their properties were briefly compared to those of the structurally quite similar PPD-based polymers (P1 and P2) with an n-octyl (linear alkyl) group on the PPD unit, in order to understand the importance of the pyrrole N-alkyl group. The calculated optical band gaps (Eg) and highest occupied molecular orbital energy levels of P3 and P4 were found to be around ∼0.1 eV higher and deeper, respectively, compared to those of the respective linear alkylated polymers P1 and P2. The maximum power conversion efficiency (PCE) obtained for the polymer solar cells made by using P3 or P4:PC70BM blends without any additive was around ∼2%, which was quite similar to that of the PSCs made using P1 or P2:PC70BM blends. However, P3 and P4 exhibited a notably lower PCE than that of P1 and P2, respectively, when the polymer solar cells were created with an additive. This study confirmed that the alkyl substituent on the pyrrole nitrogen of the PPD unit significantly affects the properties of the resulting polymer.


Polymer Bulletin | 2015

Opto-electrical, charge transport and photovoltaic property modulation of 2,5-di(2-thienyl)pyrrole-based polymers via the incorporation of alkyl, aryl and cyano groups on the pyrrole unit

Rajalingam Agneeswari; Kyung Hwan Roh; Vellaiappillai Tamilavan; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun

AbstractTo investigate the property modulation of 2,5-di(2-thienyl)pyrrole (TPT)-based polymers via the incorporation of alkyl, aryl or cyano groups on the TPT unit, four new polymers namely P(BDT-AlTPTH), P(BDT-AlTPTCN), P(BDT-ArTPTH) and P(BDT-ArTPTCN) containing 4,8-bis(2-ethylhexyloxy)benzo[1,2-b:4,5-b′]dithiophene (BDT) and TPT derivatives were prepared and their opto-electrical, charge transport and photovoltaic properties were studied. The opto-electrical studies suggest that the N-aryl TPT-based polymers such as P(BDT-ArTPTH) and P(BDT-ArTPTCN) displayed redshifted absorption maxima and higher highest occupied molecular orbital (HOMO) energy levels compared to those of their corresponding N-alkyl TPT-based polymers such as P(BDT-AlTPTH) and P(BDT-AlTPTCN). On the other hand, polymers P(BDT-AlTPTCN) and P(BDT-ArTPTCN) incorporating electron-accepting cyano group on TPT backbone showed blueshifted absorption maxima and deeper HOMO energy levels compared to those of polymers P(BDT-AlTPTH) and P(BDT-ArTPTH) containing hydrogen on TPT backbone. The organic field-effect transistors (OFETs) made from the synthesized polymers suggest that the TPT-based polymers containing hydrogen on TPT backbone exhibit quite similar mobility, but the incorporation of cyano group on TPT backbone notably decrease the hole mobility. The photovoltaic studies suggest that the polymer solar cells (PSCs) made from the TPT-based polymers containing hydrogen on TPT backbone give higher power conversion efficiency (PCE) than those made from their corresponding polymers incorporating cyano group on TPT backbone.


Journal of Polymer Science Part A | 2014

Pyrrolo[3,4‐c]pyrrole‐1,3‐dione‐based large band gap polymers containing benzodithiophene derivatives for highly efficient simple structured polymer solar cells

Vellaiappillai Tamilavan; Kyung Hwan Roh; Rajalingam Agneeswari; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun


Macromolecular Chemistry and Physics | 2015

Benzodithiophene‐Based Broad Absorbing Random Copolymers Incorporating Weak and Strong Electron Accepting Imide and Lactam Functionalized Pyrrolo[3,4‐c]pyrrole Derivatives for Polymer Solar Cells

Vellaiappillai Tamilavan; Kyung Hwan Roh; Rajalingam Agneeswari; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun


Polymer | 2015

Property modulation of dithienosilole-based polymers via the incorporation of structural isomers of imide- and lactam-functionalized pyrrolo[3,4-c]pyrrole units for polymer solar cells

Vellaiappillai Tamilavan; Jihoon Lee; Rajalingam Agneeswari; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun


Organic Electronics | 2016

Effects of the incorporation of an additional pyrrolo[3,4-c]pyrrole-1,3-dione unit on the repeating unit of highly efficient large band gap polymers containing benzodithiophene and pyrrolo[3,4-c]pyrrole-1,3-dione derivatives

Rajalingam Agneeswari; Insoo Shin; Vellaiappillai Tamilavan; Dal Yong Lee; Shinuk Cho; Youngeup Jin; Sung Heum Park; Myung Ho Hyun

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Sung Heum Park

Pukyong National University

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Myung Ho Hyun

Pusan National University

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Youngeup Jin

Pukyong National University

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Jihoon Lee

Pukyong National University

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Seungmin Kim

Pukyong National University

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Jung-Hyun Jeong

Pukyong National University

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