Electrode interface in polymer bulk-heterojunction solar cells and novel methylamine lead iodide perovskite hybrid solar cells

  • 鄭 鈞元

學生論文: Doctoral Thesis

摘要

This thesis is divided into two part: firstly we investigated the roles of poly(ethylene oxide) polymer been used as an effective buffer with Al electrode to markedly improve the electrode interface and enhance the open-circuit voltage (VOC) and the power conversion efficiency (PCE) of poly(3-hexylthiophene) (P3HT):[6 6]-phenyl C61-butyric acid methyl ester (PCBM)-based bulk-heterojunction (BHJ) solar cells A unique process by thermally co-evaporating the poly(ethylene glycol) dimethyl ether (PEGDE Mn ca 2 000) polymer with Al metal simultaneously at different ratios in vacuum (10-6 torr) was developed to prepare the electrode buffers The VOC and PCE for devices fabricated with Al electrode are 0 44V and 1 64% respectively and largely improved to 0 58V and 4 00% applying PEGDE:Al (2:1)/Al electrode under standard 1 Sun AM 1 5 simulated solar irradiation Secondly we fabricated methylammonium lead iodide (CH3NH3PbI3)/fullerene (C60) donor/acceptor planar-heterojunction (PHJ) solar cells The deposition of a thin C60 (acceptor) layer in vacuum on CH3NH3PbI3 perovskite (donor) creates a hybrid PHJ for fabricating solar cells CH3NH3PbI3 perovskite harvests the wild range of light from visible-to-near infrared and transports the positive charges The CH3NH3PbI3/C60 PHJ devices exhibits the promising photovoltaic performance In addition the magnitudes of VOC and PCE elevate to 0 65 and 0 75 V 2 4 % and 2 1 % using PCBM and indene-C60 bisadduc (ICBA) respectively of higher lowest unoccupied molecular orbital (LUMO) level instead of C60 as the acceptor These results verify the functions of CH3NH3PbI3 perovskite/C60 or C60 derivatives PHJ to the modulation of the photovoltaic parameters and the development of newly designed hybrid efficient solar cells We also find the difference between the highest occupied molecular orbital (HOMO) level of CH3NH3PbI3 perovskite and the Fermi level of ITO dominates the voltage output of the device With ITO films on glass or on the polyethylene terephthalate (PET) flexible substrate with different work functions we show significant VOC enhancement (920mV) Applying a thin nickel-oxide (NiOx) interlayer between glass/ indium-tin-oxide (ITO) electrode and light absorbing CH3NH3PbI3 perovskite significantly increases the photovoltaic performance of perovskite/fullerene-derivative PHJ solar cells First NiOx electrode-interlayer is a p-type semiconductor of high work function of 5 4 eV which is close to the valence band edge level of CH3NH3PbI3 perovskite (5 4 eV) The alignment of energy level minimizes the interfacial energy losses for the hole transfer and optimizes the photovoltage output of device Second CH3NH3PbI3 perovskite films prepared by the spin-coating process on glass/ITO/NiOx substrate exhibit a relatively smooth morphology than those deposited on glass/ITO/ PEDOT:PSS substrate The conformal coverage of the perovskite film enhances the light harvesting reduces the leakage current increases JSC and elevates the PCE of the devices The best performing cell with the configuration of glass/ITO/NiOx/CH3NH3PbI3 perovskite/PCBM/bathocuproine/Al presents a VOC = 0 92 V a JSC = 12 43 mA/cm2 and a FF = 0 68 corresponding to a PCE of 7 8 %
獎項日期2014 八月 5
原文English
監督員Tzung-Fang Guo (Supervisor)

引用此

Electrode interface in polymer bulk-heterojunction solar cells and novel methylamine lead iodide perovskite hybrid solar cells
鈞元, 鄭. (Author). 2014 八月 5

學生論文: Doctoral Thesis