Photovoltaic properties of low-band-gap fluorene-based donor-acceptor copolymers

The photovoltaic properties of three fluorene-thiophene-based donor-acceptor copolymers with low band gap and reasonably high hole mobility were studied in copolymer/[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) bulk-heterojunction photovoltaic cells. The copolymers were poly[2,7-(9,9′-dihexylfluorene)-alt-2,3-dimethyl-5,7-dithien-2-yl-quinoxaline] (PFDDTQ) (band gap = 1.94 eV; mobility = 2.83 × 10^− 5 cm² V^− 1 s^− 1), poly[2,7-(9,9′-dihexylfluorene)-alt-4,7-dithien-2-yl-2,1,3-benzothiadiazole] (PFDTBT) (band gap = 1.82 eV; mobility = 4.71 × 10^− 5 cm² V^− 1 s^− 1) and poly[2,7-(9,9′-dihexylfluorene)-alt-2,3-dimethyl-5,7-dithien-2-yl-thieno[3,4-b] pyrazine] (PFDDTTP) (band gap = 1.68 eV; mobility = 1.18 × 10^− 4 cm² V^− 1 s^− 1). The order in the short-circuit current density and power-conversion efficiency of the photovoltaic cells was PFDTBT > PFDDTQ > PFDDTTP, which contradicted the order in the band gap and mobility. The short-circuit current density and power-conversion efficiency (PCE) coincided instead with the order in the mobility of the copolymer/PCBM blend, where the mobility was increased for PFDTBT and PFDDTQ owing to the charge transfer with PCBM, but was decreased for PFDDTTP due to phase separation resulting from the strong intermolecular interactions of PFDDTTP. With its high blended mobility and low band gap, PFDTBT achieved a PCE of 1.1%.     

Synthesis and photovoltaic properties of new near infrared absorption polymers based on C and N-bridged dithiophene and diketopyrrolopyrrole units

Two novel diketopyrrolopyrrole-based conjugated copolymers, namely, poly{[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b′]dithiophene-2,6-diyl]-alt-[3,6-bis(bithiophen-5-yl)-2,5-di-(2-ethylhexyl)-pyrrolo[3,4-c]pyrrole-1,4-dione]} (P1) and poly{[N-(2-ethylhexyl)-dithieno[3,2-b:2′,3′-d]pyrrole-2,6-diyl]-alt-[3,6-bis(bithiophen-5-yl)-2,5-di-(2-ethylhexyl)-pyrrolo[3,4-c]pyrrole-1,4-dione]} (P2), have been designed and synthesized by Stille coupling reaction. The resulting copolymers exhibited very broad and strong absorptions in the visible and near-infrared region. Through cyclic voltammetry measurements, it was found that P1 possesses a lower highest occupied molecular orbital energy level (?5.14 eV) compared to that of P2 (?4.98 eV). The bulk heterojunction photovoltaic devices were fabricated by using the two copolymers as the donor and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as the acceptor in the active layer. The maximum power conversion efficiency of 1.48 % was obtained based on the blend of P1:PCBM = 1:3(w/w) with open circuit voltage (V _OC ) of 0.66 V and short circuit current (J _SC ) of 6.36 mA/cm², under the illumination of AM 1.5, 100 mW/cm².     

Polymer/polymer blend solar cells with 2.0% efficiency developed by thermal purification of nanoscale-phase-separated morphology

We have fabricated polymer/polymer blend solar cells consisting of poly(3-hexylthiophene) as the electron donor and poly{2,7-(9,9-didodecylfluorene)-alt-5,5-[4',7'-bis(2-thienyl)-2',1',3'-benzothiadiazole]} as the acceptor. The power conversion efficiency (PCE) was strongly dependent on solvents employed for spin coating. The best PCE of 2.0% was obtained for thermally annealed devices prepared from a chloroform solution, in contrast to devices fabricated from chlorobenzene and o-dichlorobenzene solutions. On the basis of the morphology-performance relationship in the polymer blends examined by atomic force microscopy and the photoluminescence quenching measurements, we conclude that the highly efficient performance is achieved by thermal purification of nanoscale-phase-separated domains formed by spin coating from chloroform.     

Structure and optical properties of single crystal of fluorene–thiophene oligomers

Solid-state optical properties of polymorph 2,7-(2-thienyl)-9,9-dihexylfluorene [TFT(C6)₂] and 2,7-di(2-thienyl)-9,9-cyclopentanefluorene [TFT] related to their crystal structure are reported. 3D phase of the first molecule displays a very peculiar arrangement, tetragonal system, where adjacent molecules cannot face to each other, due to fourfold alternating axis, therefore preventing close intermolecular interactions. The 3D packing of the second molecule shows a herringbone arrangement, where dimers are alternatively shifted. Both exhibit significant photoluminescence (PL), which changes in position and shape as a function of the solid state organization. Such different arrangements are related to different PL quantum yield values preliminarily determined.     

Synthesis of a red electrophosphorescent heteroleptic iridium complex and its application in efficient polymer light-emitting diodes

The preparation and characterization of a heteroleptic iridium complex [2-(benzo[b]thiophen-2-yl)pyridine]Ir(III)[2-(4H-1,2,4-triazol-3-yl)pyridine] [(Btp)₂Ir(PZ)] were reported (2-(benzo[b]thiophen-2-yl)pyridine = Btp; 2-(4H-1,2,4-triazol-3-yl)pyridine = PZ). Electrophosphorescence was investigated in the device structure [indium-tin-oxide (ITO)/poly(ethlenedioxythiophene) (PEDOT)/poly(vinylcarbazole)(PVK)/Poly(9,9-dioctylfluorenyl-2,7-diyl) end capped with dimethylphenyl (PFO): (Btp)₂Ir(PZ)/Ba/Al] by using this iridium complex as guest and PFO as host. The red electrophosphorescent devices showed a peak emission at approximately 604 nm and shoulder at 654 nm with the Commission International de'Eclairage (CIE) coordinates of (0.64, 0.35) and external quantum efficiency of 7.7% at a doping concentration of 8 wt.% without an electron-transporting material in the emitting layer.     

Synthesis and characterization of new donor-acceptor type copolymers based on fluorene derivatives for photovoltaic solar cells

In this paper, we demonstrated the successful synthesis of newly designed copolymers, C1 and C2, with donor-acceptor type structure. Both C1 and C2 copolymers contained 9,9-dioctylfluorene-2,7-bis(trimethyleneboronate) as one constructional unit to improve the solubility in common organic solvents. The other constructional unit was 2,3-bis(5-bromothiophen-2-yl)acrylonitrile (DTDBAL) for C1, while 4,7-dibromobenzo[c][1,2,5]thiadiazole unit, 5,5'-dibromo-2,2'-bithiophene unit and N1, N1-bis(4-bromophenyl)-N4,N4-bis(4-(2-phenylpropan-2-yl)phenyl)benzene-1,4-diamine are for C2. We fabricated photovoltaic devices based on the C1 and the C2 copolymers with Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer, PC70BM layer, TiOx layer, and aluminum (Al) electrode. The bulk heterojuntion photovoltaic devices using these copolymers as electron donor and PC70BM as the acceptor exhibited good device performances when measured at 100 mW cm-2. The power conversion efficiency (PCE) of the C1 device reached 0.45% with Voc, Jsc and FF of 0.51, 2.50 and 35%, respectively. The PCE of the C2 device reached 0.34% with Voc, Jsc, and FF of 0.56, 2.01 and 30%, respectively.     

Panchromatic photon-harvesting by hole-conducting materials in inorganic-organic heterojunction sensitized-solar cell through the formation of nanostructured electron channels

Additional photon-harvesting by hole transporting materials in Sb(2)S(3)-sensitized solar cell is demonstrated through the formation of electron channels in the hole transporter such as P3HT (poly(3-hexylthiophene)) and PCPDTBT(poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)) that can act as both a hole conductor and light absorber. As a result, the short-circuit current density is improved with an increment in overall efficiency. These findings provide new insights into use of light-absorbing conjugated polymers as a hole conductor in the inorganic-organic heterojunction sensitized solar cells.     

Excited-state absorption and anisotropy properties of two-photon absorbing fluorene derivatives

The electronic structure of fluorene derivatives N-(7-benzothiazol-2-yl-9,9-bis-decyl-9H-fluoren-2-yl)-acetamide (1); 9,9-didecyl-2,7-bis-(N,N-benzothiazoyl)fluorene (2); 4,4'-{[9,9-bis(ethyl)-9H-fluorene-2,7-diyl]di-2,1-ethenediyl}bis(N,N-diphenyl)benzeneamine (3); and 4,4',4"{[9,9-bis(ethyl)-9H-fluorene-2,4,7-triyl]tri-2,1-ethenediyl}tris(N,N-diphenyl)benzeneamine (4) were investigated by a steady-state spectral technique, quantum-chemical calculations, and a picosecond pump-probe method. These derivatives are of interest for their relatively high two-photon absorption. The steady-state excitation anisotropy spectra reveal the nature of the ground-state absorption bands. Semiempirical quantum-chemical calculations of the fluorene derivatives (AM1, ZINDO/S) show good agreement with experimental data. The spectral positions and alignment of various electronic transitions of derivatives 1-4 were estimated from their excited-state absorption and anisotropy spectra.     

Toward the extraction of single species of single-walled carbon nanotubes using fluorene-based polymers

High purity of (7,5) SWNTs (approximately 79% of the semisonducting SWNT ensemble) can be obtained by polymer-assisted extraction from the narrow-diameter distributed SWNTs produced by the catalyst Co-MCM-41. The fluorene-based polymers are able to selectively wrap the single-walled carbon nanotubes (SWNTs) with certain chiral angles or diameters depending on their chemical structures. Poly(9,9-dioctyfluoreny1-2, 7-diyl) and poly[(9,9-dihexylfluorenyl-2,7-diyl)-co-(9,10-anthracene)] selectively wrap SWNTs with high chiral angles (>24.5 degrees). By contrast, poly[9,9-dioctylfluorenyl-2,7-diyl)-co-1,4-benzo-{2,1'-3}-thiadiazole)] preferentially wraps the SWNTs with certain diameter (1.02-1.06 nm).     

Color combination of conductive polymers for black electrochromism

Conducting polymers that absorb three primary colors, red, green, and blue (RGB), were introduced with a yellow electrochromic polymer (Y) for the preparation of black electrochromic devices. Red poly(3-hexylthiophene) (P3HT) and blue poly(3,4-ethylenedioxythiophene) (PEDOT) were coated on one side of the electrode as a cathodically coloring electrochromic (EC) layer, while green poly(aniline-N-butylsulfonate) (PANBS) and yellow EC poly{[1,3-bis(9',9'-dihexylfluoren-20-yl)azulenyl]-alt-[2",7"-(9",9"-dihexylfluorenyl]} (PDHFA) were coated on the opposite electrode to complete a complementary EC device. The yellow PDHFA layer effectively compensated for absorption below 450 nm and above the 600 nm region, which was lacking in the RGB electrode. The resultant RGBY ECD provided a black color near the CIE black with L*, a*, and b* values of 32, -1.1, and 3.7, respectively, covering a broad absorption in the visible range in the colored state. The state of the black EC device was maintained, even after the electricity was turned off for 200 h, showing stable memory effect.     

Photo- and electroluminescence properties of fluorene-based copolymers containing electron- or hole-transporting unit

We report the photophysical and electroluminescence (EL) properties of two fluorene-based copolymers, poly{[9,9-bis(2-ethylhexyl)fluorene-2,7-diyl]-alt-[6,6′- bis(3-phenylquinoxaline)-2,2′-diyl]} (Qx-PF) and poly{[9,9-bis(2- ethylhexyl)fluorene-2,7-diyl]-alt-[N,N′-diphenyl-N,N′-bis(4-phenyl)-1,1′-biphenyl-4,4′-diamine]} (TPD-PF). The two copolymers in thin films show blue emission approximately 429-452 nm with relatively narrow bandwidth upon photoexcitation. Electroluminescence has been demonstrated using TPD-PF as the active polymer in the light-emitting electrochemical cell (LEC) with a turn-on voltage at 2.8 V and an EL efficiency of 0.002 cd/A. Due to the improved electron-transporting property, the Qx-PF-based LEC achieves the EL efficiency of 0.07 cd/A, 35 times higher than that of the TPD-PF-based device. Compared to the photoluminescence spectra, EL spectra show enhanced excimer emission, which is primarily related to self-heating of the devices during operation. The main process involved in the decrease of the light intensity during device operation is the electrochemical degradation of the polymer blend.     

A highly efficient polymer non-fullerene organic solar cell enhanced by introducing a small molecule as a crystallizing-agent

Non-fullerene organic solar cells (OSCs) have attracted tremendous interest because of their potential to replace traditional expensive fullerene-based OSCs. To further increase the power conversion efficiency (PCE), it is necessary to offset the narrow absorption of the non-fullerene materials, which is often achieved by adding an additive (>10?wt%) to form a ternary blend. However, a high ratio of the third component can often be detrimental to the active layer morphology and can increase the complexity in understanding the device physics toward rationally designed improvements. In this work, we introduce 2,4-bis-[(N,N-diisobutylamino)-2,6-dihydroxyphenyl]-4-(4-diphenyliminio) squaraine (ASSQ) in the poly [(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl) benzo [1,2-b:4,5-b′] dithiophene)-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl) benzo [1,2-c:4,5-c′] dithiophene-4,8-dione)] (PBDB-T): 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 (ITIC) as an active layer “crystallizing-agent”. Through detailed morphology characterization, we find that the addition of 4?wt% ASSQ assists ITIC organization order and promotes PDBD-T:ITIC aggregation in the preferential face-on orientation. In addition, we demonstrate that the ASSQ and PBDB-T show efficient exciton dissociation in the ternary blend over Förster resonance energy transfer (FRET). We reveal using surface potential and solubility measurements that a ASSQ-ITIC co-crystalline structure forms which facilitates a significant improvement in the device PCE, from 8.98% to 10.86%.     

The effect of helium plasma etching on polymer-based optoelectronic devices

In this paper the optoelectronic performance of selectively patterned conjugated polymers in light emitting diodes (LEDs) and photodetectors was examined. Polymers were patterned via a dry, non-reactive ion etching process using helium plasma. The polymers studied were the light-emitting poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly[9,9-di-(2′-ethylhexyl)fluorenyl-2,7-diyl], and the conducting poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate). The electroluminescent spectra of etched and unetched LEDs are almost identical. There is no correlation between He-ion etching times and LED emission spectra changes. The MEH-PPV-based photodetectors show no decrease in external quantum efficiencies due to increased etch times. Results show that using helium plasma is effective at etching these polymers at predictable rates from selected areas without damaging the working device.     

Photoinduced charge transfer and efficient solar energy conversion in a blend of a red polyfluorene copolymer with CdSe nanoparticles

We present measurements of charge transfer and the photovoltaic effect in a blend of the alternating polyfluorene copolymer poly(2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)) with branched CdSe nanoparticles. Quasi-steady-state photoinduced absorption measurements identified a long-lived charged species that formed after photoexcitation at room temperature. Photovoltaic devices based on this blend system showed a spectral response extending to 650 nm and gave a solar power conversion efficiency of 2.4% under Air Mass 1.5 Global (AM1.5G) conditions.     

Toward interaction of sensitizer and functional moieties in hole-transporting materials for efficient semiconductor-sensitized solar cells

Sb(2)S(3)-sensitized mesoporous-TiO(2) solar cells using several conjugated polymers as hole-transporting materials (HTMs) are fabricated. We found that the cell performance was strongly correlated with the chemical interaction at the interface of Sb(2)S(3) as sensitizer and the HTMs through the thiophene moieties, which led to a higher fill factor (FF), open-circuit voltage (V(oc)), and short-circuit current density (J(sc)). With the application of PCPDTBT (poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)) as a HTM in a Sb(2)S(3)-sensitized solar cell, overall power conversion efficiencies of 6.18, 6.57, and 6.53% at 100, 50, and 10% solar irradiation, respectively, were achieved with a metal mask.     

A 3-Fluoropyridine Manipulating the Aggregation and Fibril Network of Donor Polymers for Eco-Friendly Solution-Processed Versatile Organic Solar Cells

The development of eco-friendly solvent-processed organic solar cells (OSCs) suitable for industrial-scale production should be now considered the imperative research. Herein, asymmetric 3-fluoropyridine (FPy) unit is used to control the aggregation and fibril network of polymer blends. Notably, terpolymer PM6(FPy = 0.2) incorporating 20% FPy in a well-known donor polymer poly[(2,6-(4,8-bis(5-(2-ethylhexyl-3-fluoro)thiophen-2-yl)-benzo[1,2-b:4,5-b’]dithiophene))-alt-(5,5-(1’,3’-di-2-thienyl-5’,7’-bis(2-ethylhexyl)benzo[1’,2’-c:4’,5’-c’]dithiophene-4,8-dione)] (PM6) can reduce the regioregularity of the polymer backbone and endow them with much-enhanced solubility in eco-friendly solvents. Accordingly, the excellent adaptability for fabricating versatile devices based on PM6(FPy = 0.2) by toluene processing is demonstrated. The resulting OSCs exhibit a high power conversion efficiency (PCE) of 16.1% (17.0% by processed with chloroform) and low batch-to-batch variation. Moreover, by controlling the donor-to-acceptor weight ratio at 0.5:1.0 and 0.25:1.0, semi-transparent OSCs (ST-OSCs) yield significant light utilization efficiencies of 3.61% and 3.67%, respectively. For large-area (1.0 cm²) indoor OSC (I-OSC), a high PCE of 20.6% is achieved with an appropriate energy loss of 0.61 eV under a warm white light-emitting diode (3,000 K) with the illumination of 958 lux. Finally, the long-term stability of the devices is evaluated by investigating their structure–performance–stability relationship. This work provides an effective approach to realizing eco-friendly, efficient, and stable OSCs/ST-OSCs/I-OSCs.     

Conjugated fluorene based rod-coil block copolymers and their PCBM composites for resistive memory switching devices

We report the fabrication and characterization of polymer resistive switching memory devices fabricated from conjugated rod-coil poly[2,7-(9,9-dihexylfluorene)]-block-poly(2-vinylpyridine) diblock copolymers (PF-b-P2VP) and their hybrids with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM). PF(10)-b-P2VP(37) and PF(10)-b-P2VP(68)-based devices exhibited the volatile static random access memory (SRAM) characteristic with an ON/OFF current ratio up to 1 × 10(7), which was explained by the trapping/back transferring of charge carrier. PF(10)-b-P2VP(68) had a longer holding time in the ON state than PF(10)-b-P2VP(37) because of the delayed back transfer of trapping carriers originally from the longer P2VP blocks. The PCBM aggregated size in the composite thin films were effectively reduced by PF-b-P2VP compared to the homopolymer of PF or P2VP, because of the supramolecular charge transfer interaction, as evidenced by absorption and photoluminescence spectra. Their PCBM/PF-b-P2VP composite devices changed from the nonvolatile write-once-read-many-times (WORM) memory to the conductor behavior as the PCBM composition was increased. The electric-field induced charge transfer effect enabled the electrical bistable states for the applications in digital WORM memory device. The tunable memory characteristics through the block length ratio of block copolymers or PCBM composition provided the solution-processable charge storage nanomaterials for programmable high density memory device with a reducing bit cell size.     

Preparation of active layers in polymer solar cells by aerosol jet printing

Active layers of polymer solar cells were prepared by aerosol jet printing of organic inks. Various solvents and additives with high boiling points were screened for the preparation of high-quality polymer films. The effects on device performance of treating the films by thermal and solvent vapor annealing were also investigated. The components of the solvent were important for controlling the drying rate of the liquid films, reducing the number of particle-like protrusions on the film surface, and realizing high molecular ordering in the polymer phases. The optimized solar cell device with poly(3-hexylthiophene) and a C(60) derivative showed a high fill factor of 67% and power conversion efficiency of 2.53% without thermal annealing. The combination of poly[N-9-heptadecanyl-2,7-carbazole-alt-3,6-bis(thiophen-5-yl)-2,5-diethylhexyl-2,5-dihydropyrrolo-[3,4-]pyrrole-1,4-dione] and a C(70) derivative led to power conversion efficiency of 3.92 and 3.14% for device areas of 0.03 and 1 cm(2), respectively.     

Synthesis,characterization, and photovoltaic properties of acceptor–donor–acceptor organic small molecules with different terminal electron-withdrawing groups

Two soluble acceptor–donor–acceptor (A–D–A) type organic small molecules, 2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(methan-1-yl-1-ylidene)dimalononitrile (BvT-DCN) and 2,2′-(3,3′-(1E,1′E)-2,2′-(5,5′-(1E,1′E)-2,2′-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis(ethene-2,1-diyl)bis(3,4-dihexylthiophene-5,2-diyl))bis(ethene-2,1-diyl)bis(5,5-dimethylcyclohex-2-ene-3-yl-1-ylidene))dimalononitrile (BT-C6), were synthesized by Knoevenagel condensation reaction based on benzothiadiazole, thiophene, and different terminal electron-withdrawing groups. The acceptor group benzothiadiazole and donor group thiophene inside the molecules are connected by all-trans double bonds, which ensures the benzothiadiazole and thiopene groups are in the same plane and makes the molecules have a relative narrow band gap and absorb sunlight in the long wavelength. The terminal electron-withdrawing groups, malononitrile and 2-(5,5-dimethylcyclohex-2-en-1-ylidene)malononitrile (DCM), are symmetrically introduced into the molecules, respectively, to tune the energy level and extend the absorption of the molecules. The UV–Vis absorption spectrum and cyclic voltammetry measurements indicated that BT-C6 has a lower energy band gap (1.60 eV) than BvT-DCN (1.71 eV), which arises from the stronger electron-withdrawing ability of DCM group in BT-C6 than that of malononitrile group in BvT-DCN. And BvT-DCN and BT-C6 have nearly the same highest occupied molecular orbital energy level, ?5.74 eV for BvT-DCN and ?5.72 eV for BT-C6 due to the same electron–donor group of the two compounds. Bulk heterojunction photovoltaic devices were fabricated using BvT-DCN or BT-C6 as donor and (6,6)-phenyl C₆₁-butyric acid methyl ester as acceptor. The device based on BT-C6 has a higher (~8 times) short circuit current and power conversion efficiency than the device based on BvT-DCN, resulting from the wider solar light absorption of BT-C6 and smaller phase separation dimension of the active layer based on BT-C6.     

Probing the nanoscale phase separation and photophysics properties of low-bandgap polymer:fullerene blend film by near-field spectroscopic mapping

The effect of the additive 1,8-octanedithiol (ODT) on the nanometer-scale morphology and local photophysical properties of low-bandgap polymer blends of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b'] dithiophene)- alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) and [6,6]-phenyl C(61) -butyric acid methyl ester (PCBM) is investigated. Phase separations of the PCPDTBT:PCBM blend film induced by ODT are visualized by the morphological changes from fibril-shaped features to spherical bumps, by the dramatically increased photoluminescence emission from PCPDTBT that was originally largely quenched, and by the fluctuations of spectral features at different locations of the sample surface. The correlations between the morphology and the local photophysical properties of the blend film with/without ODT at both the micrometer and nanometer scales are revealed by confocal and high-resolution near-field spectroscopic mapping techniques.