Synthesis, Conformational Analysis, and Antiarrhythmic Properties of Selected 3-selena- 7-azabicycl0[3.3.1]Nonanes and Derivatives

Chemistr

에너지변환을 위한 도너-억셉터 시스템 내에서의 여기상태의 다이나믹스

학위논문 (박사)-- 서울대학교 대학원 : 화학부 고분자화학 전공, 2016. 2. Frédéric Laquai.현 논문은 ultrafast time-resolved optical spectroscopy를 이용하여 에너지 변환 도너-억셉터 시스템 내의 excited-state dynamics를 다루었다. 현 연구는 bulk-heterojunction morphology를 구성하는 도너 역할의 diketopyrrolopyrrole-based (DPP) low-bandgap copolymer와 억셉터 역할의 fullerene이 혼합된 유기태양전지의 photophysics를 보고하고자 한다. 두 번째 파트는 long-lived charge-separated states을 형성하기 위해 집광성 물질의 porphyrins, 전자받개 quinones과 전자주개 ferrocenes을 사용한 인공 광합성 반응을 주로 다루었다. Time-resolved photoluminescence spectroscopy 와 transient absorption spectroscopy를 이용하여, low-bandgap polymers PTDPP-TT와 PFDPP-TT 내에서 singlet-exciton의 lifetimes이 20ps 미만임을 밝히고, 폴리머와 PC71BM의 blend 상에서 bound charge-transfer states의 geminate recombination이 주요한 loss channel 임을 보고하였다. 또한, polymers triplet states내로 자유전하의 빠른 non-geminate recombination이 두 blend system에서 모두 관찰되었다. PDPP5T:PC71BM 도너-억셉터 시스템 내에서, 높은 끓는 점을 가지는 두 용액 (i.e. ortho-dichlorobenzene (o-DCB))을 사용한 polymer:fullerene blend는 active layer의 모폴로지를 급격하게 변화시키고 태양전지의 효율을 증가시킨다. 이는 친밀히 섞인 도너/억셉터 물질과 전극으로의 뛰어난 percolation으로 인하여 용이한 전하 생성과 extraction을 야기하기 때문이다. Polymer triplet state이 triplet charge-transfer states로부터 형성된 것과 같이 PDPP5T:PC71BM blend system에서 빠른 triplet-state 형성이 관찰되었다. Multivariate curve resolution (MCR) 분석은 전하의 non-geminate recombination이 폴리머 triplet-state과 밀접하게 의존하고 있음을 보여주었다. 인공적인 광합성 반응시, transient absorption spectroscopy은 photoinduced charge transfer이 quinone-porphyrin-ferrocene (Q-P-Fc) triads에서와 같이 quinone-porphyrin (Q-P)와 porphyrin-ferrocene (P-Fc) diads내에서 매우 효과적임을 증명하였다. 그러나 P-Fc 와 Q-P-Fc system내에서 전하분리상태는 각각의 porphyrin triplet state와 재결합함을 보여주었다. 현 논문은 ultrafast time-resolved optical spectroscopy를 이용하여 에너지 변환 도너-억셉터 시스템 내의 excited-state dynamics를 다루었다. 현 연구는 bulk-heterojunction morphology를 구성하는 도너 역할의 diketopyrrolopyrrole-based (DPP) low-bandgap copolymer와 억셉터 역할의 fullerene이 혼합된 유기태양전지의 photophysics를 보고하고자 한다. 두 번째 파트는 long-lived charge-separated states을 형성하기 위해 집광성 물질의 porphyrins, 전자받개 quinones과 전자주개 ferrocenes을 사용한 인공 광합성 반응을 주로 다루었다. Time-resolved photoluminescence spectroscopy 와 transient absorption spectroscopy를 이용하여, low-bandgap polymers PTDPP-TT와 PFDPP-TT 내에서 singlet-exciton의 lifetimes이 20ps 미만임을 밝히고, 폴리머와 PC71BM의 blend 상에서 bound charge-transfer states의 geminate recombination이 주요한 loss channel 임을 보고하였다. 또한, polymers triplet states내로 자유전하의 빠른 non-geminate recombination이 두 blend system에서 모두 관찰되었다. PDPP5T:PC71BM 도너-억셉터 시스템 내에서, 높은 끓는 점을 가지는 두 용액 (i.e. ortho-dichlorobenzene (o-DCB))을 사용한 polymer:fullerene blend는 active layer의 모폴로지를 급격하게 변화시키고 태양전지의 효율을 증가시킨다. 이는 친밀히 섞인 도너/억셉터 물질과 전극으로의 뛰어난 percolation으로 인하여 용이한 전하 생성과 extraction을 야기하기 때문이다. Polymer triplet state이 triplet charge-transfer states로부터 형성된 것과 같이 PDPP5T:PC71BM blend system에서 빠른 triplet-state 형성이 관찰되었다. Multivariate curve resolution (MCR) 분석은 전하의 non-geminate recombination이 폴리머 triplet-state과 밀접하게 의존하고 있음을 보여주었다. 인공적인 광합성 반응시, transient absorption spectroscopy은 photoinduced charge transfer이 quinone-porphyrin-ferrocene (Q-P-Fc) triads에서와 같이 quinone-porphyrin (Q-P)와 porphyrin-ferrocene (P-Fc) diads내에서 매우 효과적임을 증명하였다. 그러나 P-Fc 와 Q-P-Fc system내에서 전하분리상태는 각각의 porphyrin triplet state와 재결합함을 보여주었다.This thesis covers the investigation of excited-state dynamics in donor-acceptor systems for energy conversion by means of ultrafast time-resolved optical spectroscopy. The main part of this work focuses on the photophysics of organic solar cells consisting of diketopyrrolopyrrole-based (DPP) low-bandgap copolymers as electron donors blended with fullerenes as electron acceptors in a bulk-heterojunction morphology. A second part is dedicated to the study of artificial primary photosynthetic reaction centers based on porphyrins, quinones and ferrocenes as light harvesting, electron accepting, and electron donating moiety, respectively, with the aim to create long-lived charge-separated states. Time-resolved photoluminescence spectroscopy and transient absorption spectroscopy revealed that singlet-exciton lifetimes in the low-bandgap polymers PTDPP-TT and PFDPP-TT are short (< 20 ps) and that in blends of the polymers with PC71BM geminate recombination of bound charge-transfer states is a major loss channel. In addition, fast non-geminate recombination of free charges into the polymers triplet states was observed in both blend systems. For the PDPP5T:PC71BM donor-acceptor system it was found that processing the polymer:fullerene blend with a high-boiling point co-solvent, i.e. ortho-dichlorobenzene (o-DCB), drastically changes active layer morphology and increases solar cell performance, due to more intimately mixed donor and acceptor materials and pronounced percolation pathways to the electrodes, facilitating charge carrier generation and extraction. Fast triplet-state formation was observed in both of the PDPP5T:PC71BM blend systems, as the polymer triplet state can be populated from triplet charge-transfer states. Multivariate curve resolution (MCR) analysis showed a strong fluence dependence pointing to non-geminate recombination of charges into the polymer triplet state. On the artificial primary photosynthetic reaction centers transient absorption spectroscopy verified that photoinduced charge transfer is efficient in quinone-porphyrin (Q-P) and porphyrin-ferrocene (P-Fc) diads as well as in quinone-porphyrin-ferrocene (Q-P-Fc) triads. However, it was also shown that in the P-Fc and Q-P-Fc systems the charge-separated states recombine into the respective porphyrin triplet state. The charge-separated state in the Q-P diad could significantly be stabilized upon the addition of a Lewis acid.1 introduction 1 2 theoretical background 5 2.1 Organic semiconductors 5 2.2 Absorption and emission of electromagnetic radiation by molecular systems 6 2.2.1 Absorption, induced and spontaneous emission - Einstein coefficients 6 2.2.2 Selection rules and Franck-Condon Principle 9 2.2.3 Experimental aspects of absorption 12 2.3 Radiative and non-radiative transitions 13 2.3.1 Internal conversion 14 2.3.2 Fluorescence 15 2.3.3 Intersystem crossing 16 2.3.4 Phosphorescence 16 2.4 Excitons and energy transfer 17 2.4.1 Exciton models 17 2.4.2 Frster energy transfer 19 2.4.3 Dexter energy transfer 21 2.5 Organic solar cells 22 2.5.1 Working principle 22 2.5.2 Architecture of organic solar cells 23 2.5.3 Schottky contact versus Ohmic contact 25 2.5.4 Characterization of organic solar cells 25 2.6 Photophysical processes in organic solar cells 30 2.6.1 Charge transfer and charge dissociation 30 2.6.2 Charge carrier mobility 35 2.6.3 Loss channels in organic solar cells 37 2.7 Materials for organic solar cells 40 2.7.1 Donor materials 41 2.7.2 Acceptor materials 42 2.7.3 Low bandgap polymers 44 2.7.4 Design strategies for low-bandgap polymers 47 2.7.5 DPP-based donor-acceptor copolymers 49 3 experimental methods 55 3.1 Solar cell preparation 55 3.2 Solar cell characterization 57 3.2.1 Current-voltage characteristics 57 3.2.2 External quantum efficiency measurements 57 3.3 Steady state UV-vis absorption spectroscopy 57 3.4 Quasi steady-state photoinduced absorption spectroscopy 57 3.5 Transient absorption spectroscopy 59 3.5.1 Signals in transient absorption spectroscopy 59 3.5.2 Experimental setup 61 3.5.3 Multivariate curve resolution 62 3.6 Time-resolved photoluminescence spectroscopy 64 3.7 Time-of-flight technique 65 4 triplet state formation in dpp-type copolymer/PC71BM blends 69 5 photophysics of PDPP5T:PC71BM solar cells 85 5.1 Introduction 85 5.2 Photovoltaic Performance 88 5.3 Surface Morphology of PDPP5T:PC71BM blend films 90 5.4 PCBM Exciton Dynamics in PDPP5T:PC71BM blend films 92 5.5 Exciton Dynamics in pristine PDPP5T films 94 5.6 Charge- and triplet-induced absorption spectra of PDPP5T 98 5.6.1 Oxidation Study on PDPP5T 98 5.6.2 Triplet-state dynamics in a PDPP5T thin film doped with palladium-tetraanthraporphyrin 100 5.7 Charge generation and triplet-state formation in PDPP5T:PC71BM 102 5.7.1 Charge generation and triplet-state formation on the sub-ns timescale 102 5.7.2 Triplet-state formation by non-geminate recombination of charges on the sub-ns timescale 109 5.8 Charge and triplet exciton recombination on the ns-timescale 114 5.9 Charge Carrier Mobility in the PDPP5T Polymer 118 5.9.1 Field dependence of the hole mobility in pristine PDPP5T determined by the time-of-flight technique 118 5.9.2 Influence of the annealing temperature on the field-effect mobility in pristine PDPP5T 121 5.10 Conclusions 124 6 photoinduced electron transfer in anthraquinoneporphyrin-ferrocens 127 7 modular porphyrin-ferrocene and porphyrin-ferroceneporphyrin 147 8 discussion 163 8.1 Factors limiting the device efficiency in PTDPP-TT and PFDPP-TT based solar cells 163 8.2 Morphology and performance of PDPP5T:PC71BM devices 165 8.3 Triplet state formation in low-bandgap/fullerene photovoltaic blends 168 bibliography 171Docto