共轭高分子中激子形成的非绝热动力学研究
|
摘要
有机共轭高分子被光激发后,其电子结构会发生明显的变化,通过非绝热数值计算的方法模拟了受光激发后有机高分子中激子生成的动力学过程.结果表明,激子的生成一般需要数十飞秒时间,激子的生成周期随分子链长度的增大而增大.高激发态激子可以根据生成周期分为两类,第一类激子的生成周期在数十到上百飞秒之间,第二类激子的生成周期可达上千飞秒.对于超过200个碳原子的高分子,第二类激子的生成周期可达5000飞秒以上.这个计算结果说明,相比于有机高分子,有机小分子中更容易观测到激子.
After photo-excitation,the electronic structure of organic conjugated polymers will change greatly.A nonadiabatic numerical method is used to study the dynamical process of exciton formation in photo-excited polymers.It shows that exciton formation generally covers several tens of femtoseconds.In addition,the creation period increases with the increasing length of the polymer chain.Highly excited excitons can be classified into two types according to creation period.For one type,the creation period varies from several tens of femtoseconds to more than one hundred femtoseconds.For the other,the creation period can be over one thousand femtoseconds.For the polymers including more than 200 monomers,the creation period can exceed 5000 femtoseconds.This result indicates that excitons can be more readily found in oligomers than in polymers.
After photo-excitation,the electronic structure of organic conjugated polymers will change greatly.A nonadiabatic numerical method is used to study the dynamical process of exciton formation in photo-excited polymers.It shows that exciton formation generally covers several tens of femtoseconds.In addition,the creation period increases with the increasing length of the polymer chain.Highly excited excitons can be classified into two types according to creation period.For one type,the creation period varies from several tens of femtoseconds to more than one hundred femtoseconds.For the other,the creation period can be over one thousand femtoseconds.For the polymers including more than 200 monomers,the creation period can exceed 5000 femtoseconds.This result indicates that excitons can be more readily found in oligomers than in polymers.
引文
[1]Shuai Z,Beljonne D,Silbey R J,et al.Singlet and triplet exction formation rates in conjugated polymer light-emitting diodes[J].Phys.Rev.Lett.,2000,84:131.
[2]Lane P A,Wei X,Vardeny Z V.Studies of charged excitations inπ-conjugated oligomers and polymers by optical modulation[J].Phys.Rev.Lett.,1996,77:1544.
[3]Lee C H,Yu G,Heeger A J.Persistent photoconductivity in poly(p-pheneylenevinylene):spectral response and slow relaxation[J].Phys.Rev.B,1993,47:15543.
[4]Song S L,Li C M,Chan-Park M B,et al.Exciton dissociation in organic light emitting diodes at the donor-acceptor interface[J].Phys.Rev.Lett.,2007,98:176403.
[5]Banerji N,Cowan S,Leclerc M,et al.Exciton formation,relaxation,and decay in PCDTBT[J].J.Am.Chem.Soc.,2010,132:17459.
[6]Wang X L,Qiu Y.Exciton migration induced by scattering with a polaron in conjugated polymers[J].J.At.Mol.Phys.,2012,29:295(in Chinese)[王晓磊,邱宇.共轭高聚物中极化子散射引起的激子迁移[J].原子与分子物理学报,2012,29:295]
[7]Zhang Y Q,Li Y,Li D M,et al.Study on the collision of polaron pairs in the degenerate polymers[J].J.At.Mol.Phys.,2008,25:161(in Chinese)[张永强,李宏,程杰,等.基态简并聚合物中极化子对的碰撞研究[J].原子与分子物理学报,2008,25:161]
[8]Cheng J,Li H,Feng M C,et al.Dynamics of the polaron and bipolaron in nondegenerate polymers(I)[J].J.At.Mol.Phys.,2004,21:270(in Chinese)[程杰,李宏,冯名诚,等.基态非简并聚合物中的极化子和双极化子的动力学(I)[J].原子与分子物理学报,2004,21:270]
[9]Sun X.Solitons and polarons in polymers[M].Chengdu:Sichuan Education Press,1987(in Chinese)[孙鑫.高聚物中的孤子与极化子[M].成都:四川教育出版社,1987]
[10]Zhou F J,Qiu Y.Convergence in self-consistent study of polaron formation in conjugated polymers[J].J.At.Mol.Phys.,2011,28:415(in Chinese)[周芳军,邱宇.共轭高聚物中极化子形成的自洽迭代收敛性[J].原子与分子物理学报,2011,28:415]
[10]Yu J P,Qiu Y.The influence of molecular elasticity on charge transport in one-dimensional diblock copolymers[J].J.At.Mol.Phys.,2011,28:765(in Chinese)[俞建平,邱宇.一维二嵌段高聚物中电荷输运的分子弹性效应[J].原子与分子物理学报,2011,28:765]
[11]Qiu Y,Zhu L P.Field effect on polaron dynamics and charge transport in conducting polymers[J].J.Chem.Phys.,2009,131:134903.
[12]Shou Y P,Qiu Y.Thermal effects on charge transport along a conjugated polymer chain[J].J.At.Mol.Phys.,2016,33:189(in Chinese)[寿渊鹏,邱宇.共轭高分子链中电荷迁移的热效应[J].原子与分子物理学报,2016,33:189]
[13]Qiu Y.Interchian interaction effect upon the absorption spectrum in conjugated polymers[J].J.At.Mol.Phys.,2017,34:799(in Chinese)[邱宇.高聚物中分子相互作用对红外吸收谱的影响[J].原子与分子物理学报,2017,34:799]
[14]Heeger A J,Kivelson S,Schrieffer J R,et al.Solitons in conducting polymers[J].Rev.Mod.Phys.,1988,60:781.
[15]Johansson A A,Stafstrom S.Nonadiabatic simulations of polaron dynamics[J].Phys.Rev.B,2004,69:235205.
[2]Lane P A,Wei X,Vardeny Z V.Studies of charged excitations inπ-conjugated oligomers and polymers by optical modulation[J].Phys.Rev.Lett.,1996,77:1544.
[3]Lee C H,Yu G,Heeger A J.Persistent photoconductivity in poly(p-pheneylenevinylene):spectral response and slow relaxation[J].Phys.Rev.B,1993,47:15543.
[4]Song S L,Li C M,Chan-Park M B,et al.Exciton dissociation in organic light emitting diodes at the donor-acceptor interface[J].Phys.Rev.Lett.,2007,98:176403.
[5]Banerji N,Cowan S,Leclerc M,et al.Exciton formation,relaxation,and decay in PCDTBT[J].J.Am.Chem.Soc.,2010,132:17459.
[6]Wang X L,Qiu Y.Exciton migration induced by scattering with a polaron in conjugated polymers[J].J.At.Mol.Phys.,2012,29:295(in Chinese)[王晓磊,邱宇.共轭高聚物中极化子散射引起的激子迁移[J].原子与分子物理学报,2012,29:295]
[7]Zhang Y Q,Li Y,Li D M,et al.Study on the collision of polaron pairs in the degenerate polymers[J].J.At.Mol.Phys.,2008,25:161(in Chinese)[张永强,李宏,程杰,等.基态简并聚合物中极化子对的碰撞研究[J].原子与分子物理学报,2008,25:161]
[8]Cheng J,Li H,Feng M C,et al.Dynamics of the polaron and bipolaron in nondegenerate polymers(I)[J].J.At.Mol.Phys.,2004,21:270(in Chinese)[程杰,李宏,冯名诚,等.基态非简并聚合物中的极化子和双极化子的动力学(I)[J].原子与分子物理学报,2004,21:270]
[9]Sun X.Solitons and polarons in polymers[M].Chengdu:Sichuan Education Press,1987(in Chinese)[孙鑫.高聚物中的孤子与极化子[M].成都:四川教育出版社,1987]
[10]Zhou F J,Qiu Y.Convergence in self-consistent study of polaron formation in conjugated polymers[J].J.At.Mol.Phys.,2011,28:415(in Chinese)[周芳军,邱宇.共轭高聚物中极化子形成的自洽迭代收敛性[J].原子与分子物理学报,2011,28:415]
[10]Yu J P,Qiu Y.The influence of molecular elasticity on charge transport in one-dimensional diblock copolymers[J].J.At.Mol.Phys.,2011,28:765(in Chinese)[俞建平,邱宇.一维二嵌段高聚物中电荷输运的分子弹性效应[J].原子与分子物理学报,2011,28:765]
[11]Qiu Y,Zhu L P.Field effect on polaron dynamics and charge transport in conducting polymers[J].J.Chem.Phys.,2009,131:134903.
[12]Shou Y P,Qiu Y.Thermal effects on charge transport along a conjugated polymer chain[J].J.At.Mol.Phys.,2016,33:189(in Chinese)[寿渊鹏,邱宇.共轭高分子链中电荷迁移的热效应[J].原子与分子物理学报,2016,33:189]
[13]Qiu Y.Interchian interaction effect upon the absorption spectrum in conjugated polymers[J].J.At.Mol.Phys.,2017,34:799(in Chinese)[邱宇.高聚物中分子相互作用对红外吸收谱的影响[J].原子与分子物理学报,2017,34:799]
[14]Heeger A J,Kivelson S,Schrieffer J R,et al.Solitons in conducting polymers[J].Rev.Mod.Phys.,1988,60:781.
[15]Johansson A A,Stafstrom S.Nonadiabatic simulations of polaron dynamics[J].Phys.Rev.B,2004,69:235205.