Diiodooctane Research Articles

Water-Processed Organic Solar Cell with Efficiency Exceeding 11.

Water processing is an ideal strategy for the ecofriendly fabrication of organic photovoltaics (OPVs) and exhibits a strong market−driven demand. Here, we report a state−of−the−art active material, namely PM6:BTP−eC9, for the synthesis of water−borne nanoparticle (NP) dispersion towards ecofriendly OPV fabrication. The surfactant−stripping technique, combined with a poloxamer, facilitates purification and eliminates excess surfactant in water−dispersed organic semiconducting NPs. The introduction of 1,8−diiodooctane (DIO) for the synthesis of surfactant−stripped NP (ssNP) further promotes a percolated microstructure of the polymer and NFA in each ssNP, yielding water−processed OPVs with a record efficiency of over 11%. The use of an additive during water−borne ssNP synthesis is a promising strategy for morphology optimization in NP OPVs. It is believed that the findings in this work will engender more research interest and effort relating to water−processing in preparation of the industrial production of OPVs.

Role of DIO vis-à-vis microstructural kinetics during thermal annealing on the performance of PTB7:PC71BM organic solar cells

Thermal annealing is an important process to improve the power conversion efficiency (PCE) of bulk-hetero junction organic solar cells (BHJ OSCs) by inducing micro-structural changes within the active layer blend’s constituents leading to amelioration of charge transfer/transport dynamics and interfacial properties. This work investigates the impact of thermal annealing on the photovoltaic performance ofPoly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7):[6,6]-Phenyl C71-butyric acidmethyl ester(PC71BM) (PTB7:PC71BM) thin film blend in the presence of DIO (1,8 –Diiodooctane) additive, at different annealing temperatures (40, 60 and 80 °C) and correlates with the performance of DIO-free devices investigated under similar annealing conditions. Our results show that DIO-containing (w/DIO)blends, annealed at moderate temperature (40 °C) for 1 h exhibit significantly improved short circuit current (Jsc)as well as fill factor (FF) and hence 25% improvement in PCE over bench dried (unannealed) DIO-containing blend films. Interestingly, thermal treatment of DIO containing blend films at a higher temperature of 80 °C results in significant reduction of FF. However, for without DIO (w/o DIO) devices, FF remains unchanged while decrease in Jsc is significant. The inferior performance of both (w/DIO and w/o DIO) the devices at higher temperatures ~80 °C emanates from an unfavorable distribution of the polymer- fullerene network, as shown by morphological and surface potential analyses. Specifically, in w/DIO devices, the decreased performance is possibly induced by the temperature driven, accelerated loss of DIO additive that produces the evolution of undesirable morphology thus deteriorating the performance.

Selective Wet-Etching of Polymer/Fullerene Blend Films for Surface- and Nanoscale Morphology-Controlled Organic Transistors and Sensitivity-Enhanced Gas Sensors.

Surface and nanoscale morphology of thin poly(3-hexylthiophene) (P3HT) films are effectively controlled by blending the polymer with a soluble derivative of fullerene, and then selectively dissolving out the fullerene from the blend films. A combination of the polymer blending with fullerene and a use of diiodooctane (DIO) as a processing additive enhances the molecular ordering of P3HT through nanoscale phase separation, compared to the pristine P3HT. In organic thin-film transistors, such morphological changes in the blend induce a positive effect on the field-effect mobility, as the mobility is ~5–7 times higher than in the pristine P3HT. Simple dipping of the blend films in butyl acetate (BA) causes a selective dissolution of the small molecular component, resulting in a rough surface with nanoscale features of P3HT films. Chemical sensors utilizing these morphological features show an enhanced sensitivity in detection of gas-phase ammonia, water, and ethanol.

Revealing Hidden UV Instabilities in Organic Solar Cells by Correlating Device and Material Stability

AbstractWith state‐of‐the‐art organic solar cells (OSCs) surpassing 16% efficiency, stability becomes critical for commercialization. In this work, the power of using photoluminescence (PL) measurements on plain films is demonstrated, as well as high‐performance liquid chromatography analysis to reveal the origin of UV instabilities in OSCs based on the most commonly used acceptors PC70BM ([6,6]‐phenyl‐C71‐butyric acid methyl ester), ITIC (3,9‐bis(2‐methylene‐(3‐(1,1‐dicyanomethylene)‐indanone))‐5,5,11,11‐tetrakis(4‐hexylphenyl)‐dithieno[2,3‐d:2′,3′‐d′]‐s‐indaceno[1,2‐b:5,6‐b′]dithiophene), and o‐IDTBR (indacenodithiophene‐based non‐fullerene acceptor). The UV dependent stability tests reveal instabilities in solar cells based on PC70BM and ITIC while devices based on o‐IDTBR are highly stable even under UV illumination. The analysis of solar cell devices based on charge extraction and sub‐bandgap external quantum efficiency only shows the UV‐dependent emergence of traps, while PL spectra of plain films on glass allows the disentanglement and identification of individual instabilities in multi‐component bulk‐heterojunction devices. In particular, the PL analysis demonstrates UV instabilities of PC70BM and ITIC toward the processing additive 1,8 diiodooctane (DIO). The chemical analysis reveals the in‐depth mechanism, by providing direct proof of photochemical reactions of PC70BM and ITIC with UV‐induced radicals of DIO. Based on this scientific understanding, it is shown how to stabilize PBQ‐QF:PC70BM devices.

Enhanced efficiency of polymer solar cells by improving molecular aggregation and broadening the absorption spectra

Alkylthio-substituted thiophene-based benzo[1,2-b:4,5-b']dithiophene (BDT) was used to construct PBDTS-DTBT, a medium band gap donor-acceptor (D-A) polymer with 5,6-difluoro-4,7-bis[4-(2-octyldodecyl)thiophene-2-yl]benzo[c] [1,2,5]thiadiazole (DTBT). The incorporation of sulfur atoms into the side chains not only lowered the highest occupied molecular orbital (HOMO) energy level but also improved molecular aggregation and thus afforded lower band gap (1.68 eV) with full width at half maximum (FWHM) of 170 nm in comparison to that of the analogous polymer (PBDT-DTBT) without sulfur atoms in side chains. Therefore, the bulk heterojunction polymer solar cells based on PBDTS-DTBT with 2% diiodooctane (DIO) as processing additive showed a high power conversion efficiency (PCE) of 9.73% with high open-circuit voltage (VOC, 0.93 V), large short-circuit current density (JSC, 14.23 mA/cm2) and high fill factor (FF, 0.735).

A new 2D-naphtho[1,2-b:5,6-b’]dithiophene based donor small molecules for bulk-heterojunction organic solar cells

We present design and synthesis of three new symmetrical and linear A-D-A type π-conjugated donor small molecules (2D-NDT(TPD)2, 2D-NDT(Ester)2 and 2D-NDT(Amide)2) containing two dimensional (2D) naphthodithiophene (NDT) unit as the central donor core, end-capped with electron deficient unit such as thieno[3,4c]pyrrole-4,6-dione (TPD), 2-ethylhexyl 2-cyanoacetate (Ester) and 2-cyano-N-(2-ethylhexyl)acetamide (Amide) group respectively. We characterized these small molecules and further investigated the optical, electrochemical, morphological and photovoltaic properties. When solution–processed bulk heterojunction organic solar cells are fabricated using these small molecules, the morphology of 2D-NDT(Ester)2 or 2D-NDT(Amide)2 and [6,6]-PhenylC71-butyric acid methyl ester (PC71BM) blend film was optimized using 1,8 Diiodooctane (DIO) additive. DIO additive promotes the formation of nanoscopically well-connected molecular domains in the active blend film. A device based on (1% DIO, 1:1) 2D-NDT(Ester)2:PC71BM exhibited highest the efficiency of 1.22% with a short-circuit density (Jsc) of 3.75 mA/cm2, an open circuit voltage (Voc) of 0.91 V and fill factor (FF) of 35.50. Similarly for (1% DIO, 1:3) 2D-NDT(Amide)2:PC71BM device efficiency of 0.55%, with Jsc of 2.36 mA/cm2, Voc of 0.64 V and FF of 36.95 was observed. Whereas for (1:2) 2D-NDT(TPD)2:PC71BM device, due to the improper blending and phase separation between donor and acceptor efficiency restricted to 0.33% with Jsc of 1.66 mA/cm2, Voc of 0.73 V and FF of 27.2.

Robust Processing of Small-Molecule:Fullerene Organic Solar Cells via Use of Nucleating Agents

The power conversion efficiency (PCE) of small-molecule bulk heterojunction solar cells is highly sensitive to the “ink” formulation used to produce the photoactive layer. Here we demonstrate that the addition of nucleating agents renders device fabrication notably less susceptible to the ink composition, promising a route toward more robust processing of efficient devices over large areas and enabling more facile materials screening. We selected as a model system blends of 7,7-[4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b]dithiophene-2,6-diyl]bis[6-fluoro-4-(5-hexyl-[2,2-bithiophen]-5-yl)benzo[c][1,2,5]thiadiazole](p-DTS(FBTTh2)2) as the donor and [6,6]-phenyl C71-butyric acid methyl ester (PC71BM) as the acceptor because this is one of the small-molecule OPV blends with a device performance that is most sensitive to ink formulation, especially when used with the processing aid diiodooctane (DIO). Addition of DIO is essential to obtain high device performances; however, a notable increase in device perfor...

Morphology Determines Conductivity and Seebeck Coefficient in Conjugated Polymer Blends.

The impact of nanoscale morphology on conductivity and Seebeck coefficient in p-type doped all-polymer blend systems is investigated. For a strongly phase separated system (P3HT:PTB7), we achieve a Seebeck coefficient that peaks at S ∼ 1100 μV/K with conductivity σ ∼ 3 × 10-3 S/cm for 90% PTB7. In marked contrast, for well-mixed systems (P3HT:PTB7 with 5% diiodooctane (DIO), P3HT:PCPDTBT), we find an almost constant S ∼ 140 μV/K and σ ∼ 1 S/cm despite the energy levels being (virtually) identical in both cases. The results are interpreted in terms of a variable range hopping (VRH) model where a peak in S and a minimum in σ arise when the percolation pathway contains both host and guest sites, in which the latter acts as energetic trap. For well-mixed blends of the investigated compositions, VRH enables percolation pathways that only involve isolated guest sites, whereas the large distance between guest clusters in phase-separated blends enforces (energetically unfavorable) hops via the host. The experimentally observed trends are in good agreement with the results of atomistic kinetic Monte Carlo simulations accounting for the differences in nanoscale morphology.

A Solid-State Intrinsically Stretchable Polymer Solar Cell.

An organic solar cell based on a bulk heterojunction of a conjugated polymer and a methanofullerene PC61BM or PC71BM exhibits a complex morphology that controls both its photovoltaic and mechanical compliance (flexibility and stretchability). Here, the donor-acceptor blend of poly(thieno[3,4-b]-thiophene/benzodithiophene) (PTB7) and PC71BM containing a small amount of diiodooctane (DIO) in the spin-casting solution is reported to exhibit elastic deformability. The blend comprises nanometer-size, nanocrystalline grains that are relatively uniformly distributed. Large external deformation is accommodated by relative sliding between the grains. Reorientation of the nanocrystallites and the global reorientation of the PTB7 polymer chain were observed along the stretching direction up to 100% strain, which was reversible as the blend was allowed to relax to 0% strain. The polymer solar cell based on PTB7:PC71BM:DIO with such reversible morphological changes exhibited a rubbery elasticity at room temperature. The device could be stretched up to 100% strain, and the power-conversion efficiency shows a slight increase up to 30% strain and a global increase of power generation as the photoactive area increases with strain. Solar cells were fabricated employing a layer of the PTB7:PC71BM:DIO blend sandwiched between a pair of stretchable transparent electrodes, each comprising a stack of a silver nanowire percolation network and a single-wall carbon nanotube network embedded in the surface of a poly(urethane acylate) elastomer film. The solar cells were semitransparent and could be stretched like a rubbery film by as much as 100% strain. The measured power-conversion efficiency was 3.48%, which was increased to 3.67% after one cycle of stretching to 50% strain and lowered to 2.99% after 100 stretching cycles. The total power generation from the cells was significantly increased, thanks to the expanded active area as the cells were stretched.

Correction to “Effects of Additives on the Morphology of Solution Phase Aggregates formed by Active Layer Components of High-Efficiency Organic Solar Cells”

Processing additives are used in organic photovoltaic systems to optimize the active layer film morphology. However, the actual mechanism is not well understood. Using X-ray scattering techniques, we analyze the effects of an additive diiodooctane (DIO) on the aggregation of a high-efficiency donor polymer PTB7 and an acceptor molecule PC71BM under solar cell processing conditions. We conclude that DIO selectively dissolves PC71BM aggregates, allowing their intercalation into PTB7 domains, thereby optimizing both the domain size and the PTB7–PC71BM interface.

Promoting Morphology with a Favorable Density of States Using Diiodooctane to Improve Organic Photovoltaic Device Efficiency and Charge Carrier Lifetimes

Due to the inherent challenges in probing nanoscale properties within bulk heterojunction (BHJ) active layers of organic photovoltaic (OPV) devices, the relationship between morphology and nanoscale electronic structure is not well understood. Here, we employ scanning tunneling microscopy (STM) dI/dV imaging and localized density of states (DOS) spectra to investigate the influence of additives on morphology in a high-performance OPV system. In short, we are able to correlate the use of diiodooctane (DIO) additive with significant changes to the distribution of the localized DOS, most notably a broader distribution of PCE10 polymer HOMO levels and PC70BM fullerene LUMO levels, as well as significantly smaller domain sizes and significantly higher overall device efficiencies. We further correlate this data with a nearly 3-fold increase in charge carrier lifetimes in the active layer when DIO is employed, determined by time-resolved microwave conductivity (TRMC) measurements. The results are consistent with...

Alternative benzodithiophene (BDT) based polymeric hole transport layer for efficient perovskite solar cells

Organic-inorganic perovskite cell has shown a great deal of interest in past few years due to its ability to achieve high power conversion efficiency (PCE). Use of charge transport layers such as n-type TiO2 and p-type doped spiroOMeTAD in a n-i-p device architecture has shown enhanced perovskite solar cell device performance. Use of doped spiroOMeTAD as hole transport layer in the n-i-p device structure has been effective but possess disadvantages such as complex processing, use of corrosive additives, processing in ambient air for efficient hole doping. Here we report the study of solution processed benzodithiophene based polymer PBDTT-FTTE as an alternative hole transport layer to doped small molecule spiroOMeTAD. PBDT-FTTE doped with 3% DIO (diiodooctane) achieved PCE of 11.6% which was comparable to matching PCE of 11.6% obtained from using spiroOMeTAD as hole transport layer. We showed that unlike spiroOMeTAD, polymer PBDTT-FTTE is processed inside N2 filled glove box and is easier to process as compared to spiroOMeTAD which requires processing in ambient humid air and is doped with additives mixed in corrosive solvent, causing degradation to perovskite layer underneath.

Toward High‐Temperature Stability of PTB7‐Based Bulk Heterojunction Solar Cells: Impact of Fullerene Size and Solvent Additive

The use of fullerene as acceptor limits the thermal stability of organic solar cells at high temperatures as their diffusion inside the donor leads to phase separation via Ostwald ripening. Here it is reported that fullerene diffusion is fully suppressed at temperatures up to 140 °C in bulk heterojunctions based on the benzodithiophene‐based polymer (the poly[[4,8‐bis[(2‐ethylhexyl)oxy]‐benzo[1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl][3‐fluoro‐2‐[(2‐ethylhexyl)carbonyl]‐thieno[3,4‐b]thiophenediyl]], (PTB7) in combination with the fullerene derivative [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC70BM). The blend stability is found independently of the presence of diiodooctane (DIO) used to optimize nanostructuration and in contrast to PTB7 blends using the smaller fullerene derivative PC70BM. The unprecedented thermal stability of PTB7:PC70BM layers is addressed to local minima in the mixing enthalpy of the blend forming stable phases that inhibit fullerene diffusion. Importantly, although the nanoscale morphology of DIO processed blends is thermally stable, corresponding devices show strong performance losses under thermal stress. Only by the use of a high temperature annealing step removing residual DIO from the device, remarkably stable high efficiency solar cells with performance losses less than 10% after a continuous annealing at 140 °C over 3 days are obtained. These results pave the way toward high temperature stable polymer solar cells using fullerene acceptors.

Highly Efficient, Reproducible, Uniform (CH3 NH3 )PbI3 Layer by Processing Additive Dripping for Solution-Processed Planar Heterojunction Perovskite Solar Cells.

A processing additive dripping (PAD) approach to forming highly efficient (CH3 NH3 )PbI3 (MAPbI3 ) perovskite layers was investigated. A MAPbI3 (CB/DIO) perovskite film fabricated by this approach, which included briefly dripping chlorobenzene incorporating a small amount of diiodooctane (DIO) during casting of a MAPbI3 perovskite precursor dissolved in dimethylformamide, exhibited superior smooth, uniform morphologies with high crystallinity and large grains and revealed completely homogeneous surface coverage. The surface coverage and morphology of the substrate significantly affected the photovoltaic performance of planar heterojunction (PHJ) perovskite solar cells (PrSCs), resulting in a power conversion efficiency of 11.45 % with high open-circuit voltage of 0.91 V and the highest fill factor of 80.87 %. Moreover, the PAD approach could effectively provide efficient MAPbI3 (CB/DIO) perovskite layers for highly efficient, reproducible, uniform PHJ PrSC devices without performance loss or variation even over larger active areas.

Unraveling the Fundamental Mechanisms of Solvent-Additive-Induced Optimization of Power Conversion Efficiencies in Organic Photovoltaic Devices.

The realization of controllable morphologies of bulk heterojunctions (BHJ) in organic photovoltaics (OPVs) is one of the key factors enabling high-efficiency devices. We provide new insights into the fundamental mechanisms essential for the optimization of power conversion efficiencies (PCEs) with additive processing to PBDTTT-CF:PC71BM system. We have studied the underlying mechanisms by monitoring the 3D nanostructural modifications in BHJs and correlated the modifications with the optical analysis and theoretical modeling of charge transport. Our results demonstrate profound effects of diiodooctane (DIO) on morphology and charge transport in the active layers. For small amounts of DIO (<3 vol %), DIO promotes the formation of a well-mixed donor-acceptor compact film and augments charge transfer and PCE. In contrast, for large amounts of DIO (>3 vol %), DIO facilitates a loosely packed mixed morphology with large clusters of PC71BM, leading to deterioration in PCE. Theoretical modeling of charge transport reveals that DIO increases the mobility of electrons and holes (the charge carriers) by affecting the energetic disorder and electric field dependence of the mobility. Our findings show the implications of phase separation and carrier transport pathways to achieve optimal device performances.

Removal of Residual Diiodooctane Improves Photostability of High-Performance Organic Solar Cell Polymers

Solvent additives such as diiodooctane (DIO) are becoming ubiquitous in processing high performance organic photovoltaic (OPV) active layers. Here, we investigate the effects of DIO on the long-term stability of the active layer by studying the photodegradation under ambient white light illumination of the polymer PTB7-Th in pure polymer thin films and in blend films with PC71BM. Using X-ray fluorescence, we directly detect iodine in the active layer films, indicating the presence of residual DIO after casting from solution. Additionally, we show that this residual DIO dramatically decreases the photostability of the active layer. Structural changes in the films upon illumination are probed with grazing-incidence wide-angle X-ray scattering (GIWAXS). FTIR spectroscopy is used to monitor chemical changes in the polymer structure during irradiation in the presence of DIO. Furthermore, we demonstrate that film treatment either with high vacuum (10–8 Torr) for 60 min or with a high-temperature thermal anneal ...

Conjugated polymers containing pyrimidine with electron withdrawing substituents for organic photovoltaics with high open-circuit voltage

Polymers using 6-(2-thienyl)-4H-thieno[3,2-b]indole (TTI) with high planarity were synthesized and utilized for the photovoltaics. Push-pull types of conjugated polymers (PTTICN, PTTICNR and PTTIFR) containing TTI as electron pushing unit and 2-pyriminecarbonitrile or 2-fluoropyrimidine as electron pulling unit were synthesized.We designed pyrimidine derivatives with strong electron-withdrawing group (CN or fluorine) for the generation of strong electron pulling property. By the combination with the electron pushing unit, the pyrimidines with strong electron pulling units will provide low highest occupied molecular orbital (HOMO) energy levels for higher open-circuit voltages (VOC).For the syntheses of the polymers, the electron pushing and the electron pulling units were combined by Stille coupling reaction with Pd(0)-catalyst. The polymers of PTTICN and PTTICNR with CN unit show higher VOC than the polymer with fluorine unit. The device comprising PTTICNR and PCBM (1:4) with diiodooctane (DIO) additive showed a VOC of 0.82 V, a JSC of 6.38 mA/cm2, and a fill factor (FF) of 0.53, giving a power conversion efficiency of 2.81%.

PTB7:PC71BM Bulk Heterojunction Solar Cells with Multiple Additives

We fabricated bulk-hetero junction organic solar cells based on 1,2- dichlorobenzene solutions of poly[[4,8-bis[(2- ethylhexyl)oxy]benzo[1,2-b:4,5-b′] dithiophene-2,6-diyl] [3-fluoro-2- [(2-ethylhexyl) carbonyl]thieno [3,4-b]- thiophenediyl] (PTB7): [6,6]-phenyl- C71-butyric-acid-methyl-ester (PTB7:PC71BM) with additional surfactants of diiodooctane (DIO) and dimethyl sulfoxide (DMSO). The weight ratios of DIO and DMSO relative to the total weight of PTB7:PC71BM were optimized to be 3% and 13%, respectively, and found that the solar cells with the optimized weight ratios of the DIO and DMSO additives exhibited an open circuit voltage of 0.72 V, short circuit current density of 15.63 mA/cm2, fill factor of 0.49, and power conversion efficiency of 5.47%. The significant structural changes were found from the surface morphology observation of the active layer as observed by atomic force microscopy.

Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells

The addition of polystyrene (PS), a typical insulator, is empirically shown to increase the power conversion efficiencies (PCEs) of a solution‐deposited bulk heterojunction (BHJ) molecular blend film used in solar cell fabrication: p‐DTS(FBTTh2)2/PC71BM. The performance is further improved by small quantities of diiodooctane (DIO), an established solvent additive. In this study, how the addition of PS and DIO affects the film formation of this bulk heterojunction blend film are probed via in situ monitoring of absorbance, thickness, and crystallinity. PS and DIO additives are shown to promote donor crystallite formation on different time scales and through different mechanisms. PS‐containing films retain chlorobenzene solvent, extending evaporation time and promoting phase separation earlier in the casting process. This extended time is insufficient to attain the morphology for optimal PCE results before the film sets. Here is where the presence of DIO comes into play: its low vapor pressure further extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase long after casting, ultimately leading to the best BHJ organization.

PTB7:PC71BM Bulk Heterojunction Solar Cells with Multiple Additives

Bulk-hetero junction organic solar cells with active layers based on [4,8-biz[Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b']dithiophene-2,6-diyl] [3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]-thiophenediyl] and phenyl-C71-butyric-acid-methyl-ester (PC71BM) with an additive of diiodooctane (DIO) has attracted a lot of attentions due to their high power conversion efficiencies over 9% [1]. The addition of DIO significantly improved the solar cell performance, which was considered due to the change of the nano-structure configulations by the introduction of DIO. On the other hand, the introduction of dimethyl sulfoxide (DMSO) into the dicholobenzen solution of PTB7:PC71BM used to deposit the active layers [2]. However, the influence of the DMSO introduction into the PTB7:PC71BM:DIO systems have not yet been reported to the best of our knowledge. In this work, active layers were fabricated by spin coating 1,2-dichlorobenzene (500 μl) solutions of PTB7 (5 mg): PC71BM (7.5 mg) containing 0.369 mg (3wt%) of DIO and additional DMSO with different weight ratios to the total weight of PTB7:PC71BM (12.5 mg) from 0 to 30 wt% (0 to 3.69 mg). It was found that the solar cells with 13wt% (1.60 mg) of DMSO additives exhibited the best solar cell performance of an open circuit voltage of 0.72 V, short circuit current density of 15.63 mA/cm2, fill factor of 0.49, and power conversion efficiency of 5.47%. The significant structural changes were found from the surface morphology observations of the active layers depending on the DMSO concentration as observed by atomic force microscope. [1] Z. He et al., Nat Photonics 6, (2012) 591. [2] Chu et al., Appl. Phys. Lett. 98, (2011) 253301.