Badgurjar Deepak, Duvva Naresh, Bagui Anirban, Gahlot Sapna, Pawar Ravinder, Singh Surya Prakash, Garg Ashish, Giribabu Lingamallu, Chitta Raghu
Department of Chemistry, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, Kishangarh, Ajmer, Rajasthan, 305817, India.
Polymers and Functional Materials Division, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, Telangana, 500007, India.
Photochem Photobiol Sci. 2023 Feb;22(2):379-393. doi: 10.1007/s43630-022-00322-z. Epub 2022 Oct 20.
A series of phenothiazine-C dyads containing fulleropyrrolidine tethered to C-3 position (C-PTZ and C-PTZ) or to the heteroatom N-position via either phenyl (C-Ph-PTZ and C-Ph-PTZ) or phenoxyethyl linkers (C-PhOEt-PTZ and C-PhOEt-PTZ) of the phenothiazine were synthesized and light-induced electron transfer events were explored. Optimized studies suggested that the highest molecular orbital (HOMO) resides on donor phenothiazine moiety while lowest molecular orbital (LUMO) on the acceptor fulleropyrrolidine moiety of the dyads. Optical and electrochemical properties suggested no electronic communication between the donor and acceptor moieties in the ground state. However, steady-state emission studies in solvents of varied polarity, involving selective excitation of C/C, disclosed that the emission intensity of C/C was quenched in the dyads in the increasing order, C-PTZ > C-Ph-PTZ > C-PhOEt-PTZ as a consequence of the donor-acceptor distance resulted due to spacer lengths. Also, the emission quenching is more pronounced in polar solvents such as DMF compared to a non-polar solvent, toluene. With the support of parallel electrochemical studies, the emission quenching is attributed to intramolecular photo-induced electron transfer occurring from PTZ to (C/C)* generating a radical ion pair, PTZ-C/PTZ-C. Finally, bulk heterojunction (BHJ) solar cells devices inverted fashion prepared by employing the dyads as acceptors, and PTB7 as donor, suggested that the devices prepared from C derivatives i.e., PTB7:C-PTZ and PTB7:C-PhOEt-PTZ exhibited better power conversion efficiency of 2.66% and 2.15%, respectively over C derivatives i.e., PTB7:C-PTZ and PTB7:C-PhOEt-PTZ with the efficiencies of 1.80 and 1.72%, respectively. AFM studies revealed that the poor performance of PTB7:C-PTZ- and PTB7:C-PhOEt-PTZ-based devices can be ascribed to the lower solubility of the dyads in 1,2-DCB solvent leading to rough morphology.
合成了一系列吩噻嗪 - C二元体系，其中富勒吡咯烷通过苯基（C - Ph - PTZ和C - Ph - PTZ）或吩噻嗪的苯氧乙基连接基（C - PhOEt - PTZ和C - PhOEt - PTZ）连接到C - 3位（C - PTZ和C - PTZ）或杂原子N位，并研究了光诱导电子转移事件。优化研究表明，二元体系中最高分子轨道（HOMO）位于供体吩噻嗪部分，而最低分子轨道（LUMO）位于受体富勒吡咯烷部分。光学和电化学性质表明，基态下供体和受体部分之间没有电子通信。然而，在不同极性溶剂中的稳态发射研究，包括对C/C的选择性激发，揭示了由于间隔长度导致的供体 - 受体距离，C/C的发射强度在二元体系中按C - PTZ＞C - Ph - PTZ＞C - PhOEt - PTZ的顺序猝灭。此外，与非极性溶剂甲苯相比，在极性溶剂如DMF中发射猝灭更明显。在平行电化学研究的支持下，发射猝灭归因于从PTZ到（C/C）*发生的分子内光诱导电子转移，产生自由基离子对PTZ - C/PTZ - C。最后，通过将二元体系用作受体，PTB7用作供体制备的倒置式本体异质结（BHJ）太阳能电池器件表明，由C衍生物即PTB7:C - PTZ和PTB7:C - PhOEt - PTZ制备的器件分别表现出更好的功率转换效率，分别为2.66%和2.15%，优于C衍生物即PTB7:C - PTZ和PTB7:C - PhOEt - PTZ，其效率分别为1.80%和1.72%。原子力显微镜（AFM）研究表明，基于PTB7:C - PTZ和PTB7:C - PhOEt - PTZ的器件性能较差可归因于二元体系在1,2 - 二氯苯（1,2 - DCB）溶剂中的溶解度较低，导致形貌粗糙。
