Organic photovoltaic cells: Novel organic semiconducting materials and molecular arrangement engineering

International Journal of Photoenergy

Zhang

2013

Self Cite

A series of polymer solar cells (PSCs) with P3HT:PCBM or P3HT:PCBM:Ir(btpy)3blend films as the active layer were fabricated under the same conditions. Effects of phosphorescent material Ir(btpy)3doping concentration and annealing temperature on the performance of PSCs were investigated. The short-circuit current density (Jsc) and open-circuit voltage (Voc) are increased by adopting P3HT:PCBM:Ir(btpy)3blend films as the active layer when the cells do not undergo annealing treatment. The increasedJscshould be attributed to the increase of photon harvesting induced by doping phosphorescent material Ir(btpy)3and the effective energy transfer from Ir(btpy)3to P3HT. The effective energy transfer from Ir(btpy)3to P3HT was demonstrated by time-resolved photoluminescence (PL) spectra. The increasedVocis due to the photovoltaic effect between Ir(btpy)3and PCBM. The power conversion efficiency (PCE) of PSCs with P3HT:PCBM as the active layer is increased from 0.19% to 1.49% by annealing treatment at 140°C for 10 minutes. The PCE of PSCs with P3HT:PCBM:Ir(btpy)3as the active layer is increased from 0.49% to 0.95% by annealing treatment at lower temperature at 100°C for 10 minutes.

Section: Resultsmentioning

confidence: 99%

Effect of Doping Phosphorescent Material and Annealing Treatment on the Performance of Polymer Solar Cells

International Journal of Photoenergy

Zhang

2013

Self Cite

“…Thus, the increased J sat can be attributed to the effective charge-carrier transport and collection for the pero-HSCs W/ LiSPS. [ 65 ] In the low effective voltage range, namely V eff < 0.1 V, the J ph -V eff characteristics of the two pero-HSCs showed distinct differences. The peroHSCs W/O LiSPS showed a smaller value of J ph / J sat than that of the pero-HSCs W/ LiSPS.…”

Section: Resultsmentioning

confidence: 89%

Efficient Perovskite Hybrid Solar Cells via Ionomer Interfacial Engineering

Liu

et al. 2015

Adv Funct Materials

6875wileyonlinelibrary.com cells (pero-HSCs) because of the superior optical and electrical properties of the perovskite materials [ 4,5 ] and the lowcost fabrication process and high power conversion effi ciencies (PCEs) of peroHSCs. [ 6,7 ] Mesoporous structured (MS), [ 8 ] planar heterojunction (PHJ), [ 9 ] and bulk heterojunction (BHJ) [ 10,11 ] pero-HSCs have been invented to address one of the more fundamental issues, namely, the fact that the electron diffusion length is shorter than that of the holes ( L eff, e− / L eff, h+ < 1) in CH 3 NH 3 PbI 3 perovskite, [ 12 ] for further boosting the PCEs of pero-HSCs. However, so far no solution has been found for the whole problem due to the poor electron-extraction effi ciency from the electron-extraction layer (EEL) to the electrode. [ 13,14 ] In fact, the electrical conductivities of a TiO x EEL in MS pero-HSCs and phenyl-C 61 -butyric acid methyl ester (PC 61 BM) EEL in PHJ pero-HSCs are several orders of magnitude lower than those of the hole-extraction layer (HEL) counterparts, [15][16][17][18][19][20] resulting in an inferior electron-collection effi ciency, lower shortcircuit current density ( J SC ), and lower fi ll factor (FF). [ 11,21 ] On the other hand, it has been reported that the contact between the perovskite layer and the EEL was poor due to the rough surface of the solution-processed perovskite layer, [ 22,23 ] which inevitably deteriorates the electron-extraction effi ciency, creates charge-carrier recombination, and simultaneously introduces large leakage currents. [24][25][26] In order to circumvent these problems, studies have been focused on the interfacial modifi cation of the contact between the EEL and the cathode. Improved electron transport towards the cathode has been observed from pero-HSCs incorporated with a thin layer of thermal-evaporated LiF, bathocuproin (BCP), and fullerene (C 60 ), which was inserted between the PC 61 BM EEL and the electrodes. [ 27 ] Surprisingly, however, the manipulation of the interface between the solution-processed CH 3 NH 3 PbI 3 perovskite layer and the PC 61 BM EEL has rarely been addressed. In this scenario, we employ a solution-processed ionomer, 4-lithium styrenesulfonic acid/styrene copolymer (LiSPS), to re-engineer the interface between the solution-processed CH 3 NH 3 PbI 3 perovskite layer and the PC 61 BM EEL. The introduction of such highly ionic, electrically conductive LiSPS to optimize the carrier-transport pathway results in enhanced electron-collection effi ciency. Moreover, the LiSPS possesses a good wettability Effi cient Perovskite Hybrid Solar Cells via Ionomer Interfacial EngineeringKai Wang , Chang Liu , Chao Yi , Long Chen , Jiahua Zhu , R. A. Weiss , * and Xiong Gong * The surface of the solution-processed methylammonium lead tri-iodide (CH 3 NH 3 PbI 3 ) perovskite layer in perovskite hybrid solar cells (pero-HSCs) tends to become rough during operation, which inevitably leads to deterioration of the contact between the perovskite layer and the charge-extraction layers. Mor...

“…The key parameters of PSCs are summarized in Table 1. It is apparent that Cells D have relatively larger oc than those of Cells A and B, and the oc of Cells D remain almost the same compared with that of Cells C. As we know oc of PSCs is primarily determined by two factors: (i) the energy levels difference between the HOMO International Journal of Photoenergy of the electron donor and the LUMO of electron acceptor and (ii) the work function difference between anode and cathode electrode [20]. It could be assumed that the improved oc of Cells D was due to the changes of anode work function since the active layer fabrication condition and the cathode layer deposition remain constant.…”

Section: Resultsmentioning

confidence: 92%

Ultrathin Anode Buffer Layer for Enhancing Performance of Polymer Solar Cells

International Journal of Photoenergy

et al. 2014

Self Cite

A series of polymer solar cells (PSCs) based on poly[(4,8-bis-(2-ethylhexyloxy)-benzo[1,2-b:4,5-b′(dithiophene)-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2,6-diyl] (PBDTTT-C) and [6,6]phenyl-C71-butyric acid methyl ester (PC71BM) were fabricated with various anode buffer layers. The power conversion efficiency (PCE) of PSCs was improved to 4.91% for the cells with PEDOT:PSS/LiF (1 nm) as anode buffer layer, which corresponds to 26.2% efficiency improvement compared with the cells with PEDOT:PSS as anode buffer layer. The PSCs with PEDOT:PSS/LiF as anode buffer layer show a maximum short-circuit density (Jsc) of 13.70 mA/cm2, with open circuit voltage (Voc) of 0.73 V and fill factor (FF) of 49.1% under illumination 100 mW/cm2AM 1.5 G simulated solar light. The dominant mechanism for the performance improvement of PSCs could be attributed to the increased charge carrier collection ability by anode buffer layers.