Power Conversion Efficiency Of P3HT Research Articles

Doping with Niobium Nanoparticles as an Approach to Increase the Power Conversion Efficiency of P3HT:PCBM Polymer Solar Cells.

Metal additive processing in polymer: fullerene bulk heterojunction systems is recognized as a viable way for improving polymer photovoltage performance. In this study, the effect of niobium (Nb) metal nanoparticles at concentrations of 2, 4, 6, and 8 mg/mL on poly(3-hexylthiophene-2,5-diyl) (P3HT)-6,6]-phenyl C61-butyric acid methyl ester (PCBM) blends was analyzed. The effect of Nb volume concentration on polymer crystallinity, optical properties, and surface structure of P3HT and PCBM, as well as the enhancement of the performance of P3HT:PC61BM solar cells, are investigated. Absorption of the P3HT:PC61BM mix is seen to have a high intensity and a red shift at 500 nm. The reduction in PL intensity with increasing Nb doping concentrations indicates an increase in PL quenching, suggesting that the domain size of P3HT or conjugation length increases. With a high Nb concentration, crystallinity, material composition, surface roughness, and phase separation are enhanced. Nb enhances PCBM's solubility in P3HT and decreases the size of amorphous P3HT domains. Based on the J-V characteristics and the optoelectronic study of the thin films, the improvement results from a decreased recombination current, changes in morphology and crystallinity, and an increase in the effective exciton lifespan. At high doping concentrations of Nb nanoparticles, the development of the short-circuit current (JSC) is associated with alterations in the crystalline structure of P3HT. The highest-performing glass/ITO/PEDOT:PSS/P3HT:PCBM:Nb/MoO3/Au structures have short-circuit current densities (JSC) of 16.86 mA/cm2, open-circuit voltages (VOC) of 466 mV, fill factors (FF) of 65.73%, and power conversion efficiency (µ) of 5.16%.

Effects of the PENTACENE as doping material on the power conversion efficiency of P3HT:PCBM based ternary organic solar cells

In organic solar cells (OSCs), changing the device geometry and the photophysical properties of the active layer is an effective way to change the power conversion efficiency (PCE). For this purpose, both the buffer layer was coated between the active layer and the metal and the organic material was doped to the active layer to obtain the ternary structure. In this study, for the fabrication of bulk-heterojunction (BHJ) organic solar cell, the PEDOT:PSS layer was coated on chemically cleaned ITO coated glass substrates by the spin coating method. Subsequently, the P3HT:PCBM blend as an active layer was coated on top of PEDOT:PSS in the glove box using the same method. Finally, aluminum (Al) was coated using thermal evaporation and ITO/PEDOT:PSS/P3HT:PCBM/Al organic solar cells structure as reference device were obtained. Then, PENTACENE material with an organic semiconductor property was doped into P3HT:PCBM blend and ITO/PEDOT:PSS/P3HT:PCBM:PENTACENE/Al bulk heterojunction organic solar cell structure was obtained using the same method. In addition, the effects of OSC on PCE were investigated by coating the 2 nm lithium fluoride layer between the Al and the active layer. For devices, dark and light current density-voltage (J-V) measurements were performed under 100 mW/cm2 in the glove box, and device parameters were calculated by the J-V curve. It was observed that the reference device showed photovoltaic properties under light and its PCE was 0.64%. When the experimental findings obtained were examined, both the LiF buffer layer and PENTACENE doping material improved the ternary OSC device performance and increased the PCE from 0.64% to 2.65%, according to the reference device. As a result of the doping, the mobility of the carrier increased with the increase of photon absorption and the presence of the buffer layer increased the carrier injection. Changing device properties can be explained with these results.

High-Performance Hybrid Photovoltaics with Efficient Interfacial Contacts between Vertically Aligned ZnO Nanowire Arrays and Organic Semiconductors.

Hybrid photovoltaics (HPVs) incorporating both organic and inorganic semiconducting materials have attracted much attention as next-generation photovoltaics because of their advantage of combining both materials. The hybridization of ZnO nanowires (NWs) and organic semiconductors is expected to be a suitable approach to overcome the limited exciton diffusion length and low electron mobility associated with current organic photovoltaics. The use of ZnO NWs allows researchers to tune nanoscale dimensions more precisely and to achieve rod-to-rod spacing below 10 nm. However, the perfect incorporation of organic semiconductors into densely packed ZnO NW arrays has yet to be achieved. In this study, we report the fabrication of ZnO NW arrays and various organic heterojunction-based HPVs using the feasible and effective vacuum-assisted double coating (VADC) method, achieving full coverage of the organic semiconductors on the compact ZnO NW arrays. The newly proposed VADC method ensures perfect infiltration and full coverage of the organic semiconductors on the densely packed NW arrays. Compared with the conventional single spin-coating process, the use of the VADC method led to 11 and 14% increases in the power conversion efficiency of P3HT:PCBM- and PBDTTT-C-T:PC71BM-based HPVs, respectively. Our studies provide a feasible method for the fabrication of efficient HPVs.

Effect of doping on thin film solar cell efficiency based on ZnMn2O4 nanocrystals

Abstract The present study reports, for the first time, a facile synthesis for ternary ZnMn2O4 nanocrystals synthesized by a simple and low cost two-phase method. Those nanocrystals were used on thin film solar cell as active absorber layer. The resulting nanocrystals were characterized by XRD, TEM, AFM-MFM, FTIR and JV characterization techniques to investigate the crystalline behavior, chemical composition, morphology and optical properties. Two phase method allows the successful synthesis of oleic acid (OA) capped ZnMn2O4 nanocrystals with 5-10 nm particle size. After doping of the ZnMn2O4 nanocrystals at different ratios with P3HT:PCBM, an enhancement was observed in the solar cell performances based on thin films. The power conversion efficiency of P3HT:PCBM-ZnMn2O4 thin film solar cell was investigated by J-V characteristic curve and as a result of this study, the highest efficiency was achieved as 3.27% with a doping ratio of 1%. Thus we believe that this work will open a new perspective to the synthesis of ZnMn2O4 materials for applications in the field of energy conversion systems

Light trapping and power conversion efficiency of P3HT : nano Si hybrid solar cells.

In this study, the hybrid solar cells (HSCs) were fabricated with high-purity nano Si from nano SiO2 precursor extracted from natural minerals, that is, quartz sand. The prepared nano Si was used as an electron transport material to prepare an active layer material mixture with poly(3-hexylthiophene) (P3HT) by mixing it in two composition ratios, namely 1 : 1 and 1 : 0.8. The blended active layer solutions (ALSs) were prepared by using solvents such as 1,2-dichlorobenzene (DCB), chlorobenzene (CB), and chloroform (CF). The HSCs were fabricated using six blended ALSs, namely ALS1, ALS2, ALS3, ALS4, ALS5, and ALS6. The current density–voltage characteristics of the fabricated HSCs were studied using a simulated AM 1.5G illumination having light density power of 100 mW cm−2. The characterization properties such as short circuit current density (Jsc) and power conversion efficiency (PCE) were studied and compared with those of all six HSCs fabricated with six blended ALSs. At the outset, the P3HT : nano-Si (1 : 0.8) blended ALS in CB solvent shows 2.37% PCE, and 46% of external quantum efficiency (EQE) absorption which is higher than the other fabricated solar cells. This study discusses the possibilities of preparation of nano Si from natural mineral sand, as an effective electron transport material to fabricate HSCs with enhanced PCE.

Enhancing the Efficiency of Organic Photovoltaics by a Photoactive Molecular Mediator

High boiling‐point solvent additives, such as 1,8‐diiodooctane, have been widely used to tune nanoscale phase morphology for increased efficiency in bulk heterojunction organic solar cells. However, liquid‐state solvent additives remain in the active films for extended times and later migrate or evaporate from the films, leading to unstable device performance. Here, a solid‐state photoactive molecular mediator, namely N(BAI)3, is reported that could be employed to replace the commonly used solvent additives to tune the morphology of bulk heterojunction films for improved device performance. The N(BAI)3 mediator not only resides in the active films locally to fine tune the phase morphology, but also contributes to the additional absorption of the active films, leading to ∼11% enhancement of power conversion efficiency of P3HT:PC60BM devices. Comparative studies are carried out to probe the nanoscale morphologies using grazing incidence wide‐angle X‐ray scattering and complementary neutron reflectometry. The use of 1 wt% N(BAI)3 is found to effectively tune the packing of P3HT, presumably through balanced π‐interactions endowed by its large conjugated π surface, and to promote the formation of a PC60BM‐rich top interfacial layer. These findings open up a new way to effectively tailor the phase morphology by photoactive molecular mediators in organic photovoltaics.

Influence of molar mass ratio, annealing temperature and cathode buffer layer on power conversion efficiency of P3HT:PC71BM based organic bulk heterojunction solar cell

Abstract In bulk heterojunction (BHJ) solar cells, the molar mass ratio of donor-acceptor polymers, the annealing temperature (T an ) and the cathode buffer layer plays very consequential role in improving the power conversion efficiency (PCE) by tuning the film morphology and enhancing the charge carrier dynamics. A comprehensive understanding of each of these factors is essential in order to optimize the performance of organic solar cells (OSCs). Albeit there are several fundamental reports regarding these factors, an altogether meticulous correlation of these physical processes with experimental evidence of the photo active layer are required. In this work, we systematically analyzed the influence of different molar mass ratio, the annealing temperature (T an ) and the cathode buffer layer of rrP3HT:PC 71 BM based BHJ solar cells and their corresponding photovoltaic performances were correlated carefully with their thin film growth structure and energy level diagram. The device having 1:0.8 molar mass ratio of rrP3HT:PC 71 BM and T an = 150 °C annealing temperature with Bathocuproine (BCP) as the cathode buffer layer having ITO/PEDOT:PSS/rrP3HT:PC 71 BM (molar mass ratio = 1:0.8; (T an = 150 °C)/BCP/Al) configuration showed the best device performance with PCE, ɳ = 4.79%, Jsc = 14.21 mA/cm 2 , V oc = 0.58 V and FF = 57.8%. This drastic variation in PCE of the device having BCP/Al as the cathode contact compared to the other device configurations is due to the coalesced effects of better hole-blocking capacity of BCP along with Al and better phase separation of the active blend layer at 150 °C annealing temperature. These results explicate the cumulate role of all these physical parameters and their combined contribution to the PCE amendment and overall device performance with rrP3HT:PC 71 BM based organic BHJ solar cell.

Factors determining large observed increases in power conversion efficiency of P3HT:PCBM solar cells embedded with Mo6S9−xIx nanowires

Power conversion efficiency (PCE) of bulk heterojunction solar cells is influenced by many factors, such as energy level alignment, light trapping and absorption, exciton diffusion, charge carrier mobility and non radiative recombination rate. Despite significant efforts towards improving all these aspects, the PCE remains relatively low and progress has been slow. Here we report a remarkable 52% relative increase in efficiency of solar cells embedded with small amounts of Mo6S9−xIx nanowires dispersed in P3HT:PCBM matrix. We present a detailed and systematic investigation of the numerous factors influencing this breakthrough increase in PCE. Raman spectroscopy and photocurrent imaging are used to investigate the spatial inhomogeneity of solar cell parameters and correlate them with the device performance. The largest effect appears to be improved hole mobility, which increases by a factor of 2.5. Surprisingly, only cells with highly regioregular P3HT show a dramatic effect with Mo6S9−xIx nanowires, while less regioregular P3HT:PCBM matrices show much smaller effect, pointing to level alignment as the crucial parameter in cell efficiency. A smaller PCE increase is attributed to absorbance of the active layer by surface-deposited Mo6S9−xIx nanowires.

Influences of thermal annealing on P3HT/PCBM interfacial properties and charge dynamics in polymer solar cells

The effects of thermal annealing on the interfacial properties of poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl C61 butyric acid methyl ester (PCBM) and on the charge dynamics in P3HT:PCBM polymer solar cells (PSCs) are investigated. This study determines that an effective phase separation of the P3HT and PCBM caused by thermal annealing achieves a larger interfacial area for efficient exciton dissociation and a well-defined pn junction with few defect levels at the P3HT/PCBM interface. Additionally, thermal annealing creates a compositional gradient across the P3HT:PCBM films, which enhances the charge transit ability significantly. These improved interfacial properties and efficiency in charge transit ability account for the better power conversion efficiency of P3HT:PCBM PSCs treated with thermal annealing.

Improved efficiency of organic solar cells by transfer printing induced crystallization of active layer

Stamp transfer printing process has been found to increase the efficiency of poly(3-hexylthiophene)(P3HT):indene-C60 bisadduct (ICBA) organic solar cells. Here, we show that the stamp transfer printing of P3HT:ICBA active layer on poly-(3,4-ethylenedioxythiophene); polystyrenesulfonate enhances the power conversion efficiency of P3HT:ICBA device by about 21% compared with that of spin coated devices mainly due to transfer printing induced crystallization of P3HT.

Organic Electronics: Improved Power Conversion Efficiency of P3HT:PCBM Organic Solar Cells by Strong Spin–Orbit Coupling‐Induced Delayed Fluorescence (Adv. Energy Mater. 8/2015)

Organic Electronics: Improved Power Conversion Efficiency of P3HT:PCBM Organic Solar Cells by Strong Spin–Orbit Coupling‐Induced Delayed Fluorescence (Adv. Energy Mater. 8/2015)

Enhancement of power conversion efficiency of P3HT:PCBM solar cell using solution processed Alq3 film as electron transport layer

Solution-processed thin films of tris(8-hydroxyquinoline)aluminum (Alq3) have been produced and examined as an electron transport layer in P3HT:PCBM bulk heterojunction organic solar cells. UV–Vis absorption, XRD, SEM and current density–voltage (J–V) measurements both in dark and under illumination have been carried out. Absorption spectra of the active layer show typical P3HT:PCBM absorption features with a maximum absorption peak around 500 nm and two vibronic shoulders around 550 and 600 nm which were attributed to the inter-chain stacking of P3HT. Furthermore, XRD measurements revealed that the co-solvent processed film shows better crystallinity than the mono-solvent film. On the other hand, SEM images show a clear pinholing effect in the DCB-processed film which may cause leakage current that reduces the fill factor and overall power conversion efficiency (PCE) of the organic solar cell (OSC). Alq3 absorption spectra show an absorption peak in the UV region, with an optical band gap of 2.83 eV. The incorporation of Alq3 films as an electron transport layer in ITO/PEDOT:PSS/P3HT:PCBM/Alq3/Al structure has resulted in a significant enhancement in the performance of the studied OSC devices. The use of mixed solvents of dichlorobenzene and chlorobenzene (DCB:DB) together with the inclusion of Alq3 layer has resulted in enhanced PCE which reached 3.92 %.

Simultaneous Improvement in Short Circuit Current, Open Circuit Voltage, and Fill Factor of Polymer Solar Cells through Ternary Strategy

We present a smart strategy to simultaneously increase the short circuit current (Jsc), the open circuit voltage (Voc), and the fill factor (FF) of polymer solar cells (PSCs). A two-dimensional conjugated small molecule photovoltaic material (SMPV1), as the second electron donor, was doped into the blend system of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl (PC71BM) to form ternary PSCs. The ternary PSCs with 5 wt % SMPV1 doping ratio in donors achieve 4.06% champion power conversion efficiency (PCE), corresponding to about 21.2% enhancement compared with the 3.35% PCE of P3HT:PC71BM-based PSCs. The underlying mechanism on performance improvement of ternary PSCs can be summarized as (i) harvesting more photons in the longer wavelength region to increase Jsc; (ii) obtaining the lower mixed highest occupied molecular orbital (HOMO) energy level by incorporating SMPV1 to increase Voc; (iii) forming the better charge carrier transport channels through the cascade energy level structure and optimizing phase separation of donor/acceptor materials to increase Jsc and FF.

Improved Power Conversion Efficiency of P3HT:PCBM Organic Solar Cells by Strong Spin–Orbit Coupling‐Induced Delayed Fluorescence

Solution‐processed organic bulk heterojunction solar cells based on poly(3‐hexylthiophene) (P3HT) blended with [6,6]‐phenyl‐C60‐butyric acid methyl ester are doped with different concentrations of iron (II,III) oxide nanoparticles (Fe3O4). The power conversion efficiency of the devices doped at low concentrations is improved up to 11%. The improvement finds its origin in a lower recombination current, which is a consequence of an increased effective exciton lifetime according to the J–V characteristics and the optoelectronical analysis of the films. The increase in performance cannot be attributed to changes in morphology or crystallinity according to grazing‐incidence X‐ray scattering experiments. The evolution of the solar cell short‐circuit current at low doping concentrations is related to variations in the arrangement of the crystalline regions of P3HT. For high doping concentrations (above 1.0 wt%) the performance of the solar cell decays rapidly, ascribed to the increased leakage currents in the device caused by the presence of nanoparticles.

Annealing temperature dependence of the efficiency and vertical phase segregation of polymer/polymer bulk heterojunction photovoltaic cells

We report observation of annealing temperature-induced simultaneous vertical phase segregation and large enhancement of power conversion efficiency (PCE) of all-polymer bulk heterojunction (BHJ) solar cells composed of a poly(3-hexylthiophene) (P3HT) donor and a naphthalene diimide-selenolo[3,2-b]selenophene copolymer (PNDISS) acceptor. The PCE of P3HT:PNDISS BHJ devices increased over 50-fold from 0.04% to 2.03% when the annealing temperature was increased from 50 to 150 °C. Absorption spectroscopy and photoluminescence quenching experiments provide evidence of increasing phase segregation of the polymer/polymer blend films with increasing annealing temperature. Field-effect charge transport, contact angle, surface energy, and variable angle ellipsometry measurements on the P3HT:PNDISS blend films showed that thermal annealing induced vertical phase segregation, whereby the low surface energy polymer (P3HT) migrated to the bulk, while the high surface energy polymer (PNDISS) enriches at the substrate/blend interface.

Influence of morphology of PCDTBT:PC71BM on the performance of solar cells

Because of the restriction of low energy difference between the highest occupied molecular orbital of P3HT and the lowest unoccupied molecular orbital of PCBM, the obtained power conversion efficiency of P3HT:PCBM solar cells is merely half the ideal value. In this paper, we have fabricated bulk heterojunction solar cells based on PCDTBT and PC71BM (structure: ITO/PEDOT:PSS/PCDTBT:PC71BM/LiF (0.8 nm)/Al (80 nm)). In order to optimize the performance of the cells, the weight ratio of PCDTBT to PC71BM, the thickness of the active layer and thermal annealing are investigated. When the weight ratio of PCDTBT to PC71BM is 1:2 and the thickness of the active layer is 73 nm, a short circuit current density of 10.36 mA/cm2, an open-circuit voltage of 0.91 V, a fill factor of 55.06 % and a power conversion efficiency of 5.19 % can be achieved. Moreover, we probe the influence of annealing temperature on the performance of organic solar cells, and find that the thermal treatment methodology (apart from the removal of trapped casting solvent) is of limited benefit.

Improvement of power conversion efficiency of P3HT:CdSe hybrid solar cells by enhanced interconnection of CdSe nanorods via decomposable selenourea

We introduce a novel method to improve the device performance of P3HT:CdSe hybrid solar cells by using selenourea (SeU) for ligand exchange. SeU induces interconnection of CdSe nanorods in the nanoscale range without severe aggregation. The power conversion efficiency of the devices with SeU is improved from 1.71% to 2.63% due to efficient charge transport through interconnected CdSe nanorods.

Enhancement of the power conversion efficiency of P3HT:PCBM based solar cells by an interfacial effect between P3HT and PEDOT

We report a process that enhances the power conversion efficiency (PCE) of organic solar cells based on poly(3-hexythiophene) and [6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM). In this process, the active material is maintained in the liquid state for a prolonged period of time to promote interfacial contact with the poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) buffer layer. It is observed that through this process, the PCE of the device provided a further 19% enhancement on top of the enhancement obtained by the familiar solvent annealing process. This process depends critically on the presence of the PEDOT:PSS buffer layer, and it is hypothesized that the action of this enhancement process involves interfacial interactions between P3HT and PEDOT polymers.

Indolinone-substituted methanofullerene—A new acceptor for organic solar cells

Indolinone-substituted methanofullerene, 1-(3,5-di-tret-butyl-4-hydroxybenzyl)-3-(3-cyclopropane[1,9](C60-Ih)[5,6]fullerene-3-yl)-indolin-2-one (HBIM), has been studied as an electron acceptor for polymer–fullerene solar cells. HBIM is easier to synthesize and purify than the standard fullerene derivative for polymer solar cells, PCBM. Optical absorption, solubility, and electrochemical properties of HBIM are reported. Solar cells with the device configuration ITO/PEDOT:PSS/P3HT:HBIM/CaAl have been investigated with the reference cells based on the P3HT:PCBM blend. We study the effect of thermal annealing on the device performance and the surface morphology of the active layer. The power conversion efficiency of P3HT:HBIM devices with a weight ratio of 1:1 is about 2% under illumination by AM1.5G (100 mW/cm2) radiation. The P3HT:HBIM devices show the same open-circuit voltage as the P3HT:PCBM ones, but the short-circuit current and the fill factor are considerably less.

Non‐Fullerene Acceptor‐Based Bulk Heterojunction Polymer Solar Cells: Engineering the Nanomorphology via Processing Additives

AbstractThe performance of bulk heterojunction solar cells made from blends of a non‐fullerene acceptor, N,N′‐bis(2‐ethylhexyl)‐2,6‐bis(5″‐hexyl‐[2,2′;5′,2″]terthiophen‐5yl)‐1,4,5,8‐naphthalene diimide (NDI‐3TH), and poly(3‐hexylthiophene) (P3HT) donor is enhanced 10‐fold by using a processing additive in conjunction with an electron‐blocking and a hole‐blocking buffer layers. The power conversion efficiency of P3HT:NDI‐3TH solar cells improves from 0.14% to 1.5% by using a processing additive (1,8‐diiodooctane) at an optimum concentration of 0.2 vol%, which is far below the 2‐3 vol% optimum concentrations found in polymer/fullerene systems. TEM and AFM imaging show that the size and connectivity of the NDI‐3TH domains in the phase‐separated P3HT:NDI‐3TH blends vary strongly with the concentration of the processing additive. These results demonstrate, for the first time, that processing additives can be effective in the optimization of the morphology and performance of bulk heterojunction polymer solar cells based on non‐fullerene acceptors.