Butyric Acid Methyl Ester Research Articles

Low temperature processed ternary oxide as an electron transport layer for efficient and stable perovskite solar cells

In this paper, high efficient and stable planar perovskite solar cells (PKSCs) have been designed and fabricated via employing high transparent Mg-doped ZnO films with excellent electron transport ability as a novel class of electron transport layers (ETLs). Due to the optimized band alignment by Mg doping, the photogenerated electron injection and charge extraction from the perovskite film to ETL have been facilitated effectively and the planar PKSC based on 2% Mg-doped ZnO and MAPbI3 yields the maximum power conversion efficiency (PCE) of up to 16.74%. Meanwhile, a higher PCE of 17.85% through a phenyl C60 butyric acid methyl ester (PCBM) interfacial layer between the 2% Mg-doped ZnO and perovksite layer has been achieved for the first time. Moreover, the PKSCs with 2% Mg-doped ZnO/PCBM composite ETLs also demonstrate outstanding long term device stability and up to 91% of original PCE of the PKSCs, which can be retained even after exposure in ambient conditions over three-months.

Semiconductor:Insulator Blends for Speed Enhancement in Organic Photodiodes

AbstractOrganic photodiodes (OPDs) have been studied intensively for a number of years, as they enable low‐cost fabrication of sensor systems for imaging, medical, or industrial applications. While the device performance in terms of responsivity and detectivity is continuously improving, detection speed still lags behind. One of the major limiting factors is the large transit times of the charges. In this work, an approach of blending insulating polymers into a poly(3‐hexylthiophene‐2,5‐diyl) and [6,6]‐phenyl C61 butyric acid methyl ester bulk heterojunction system, which has already shown beneficial effects on the transport properties in organic field effect transistors or organic solar cells, is followed. Starting from a basic morphological study using poly(methyl methacrylate) (PMMA) with different molecular weights, both the steady‐state and dynamic characteristics of the OPDs are examined. Transient photocurrent measurements show that the inclusion of PMMA results in an increase of the −3 dB cut‐off frequency without adversely affecting the device steady‐state performance under illumination or in the dark. This increase is attributed to a reduced transit time in the active layer when PMMA is present.

Analysis of Ion‐Diffusion‐Induced Interface Degradation in Inverted Perovskite Solar Cells via Restoration of the Ag Electrode

AbstractStraightforward evidence for ion‐diffusion‐induced interfacial degradation in inverted perovskite solar cells is presented. Over 1000 h, solar cells inevitably undergo degradation, especially with respect to the current density and fill factor. The Ag electrode is peeled off and re‐evaporated to investigate the effect of the Ag/[6,6]‐phenyl C71 butyric acid methyl ester (PCBM) interfacial degradation on the photovoltaic performance at days 10 (240 h), 20 (480 h), 30 (720 h), and 40 (960 h). The power conversion efficiency increases after the Ag electrode restoration process. While the current density shows a slightly decreased value, the fill factor and open‐circuit voltage increase for the new electrode devices. The decrease in the activation energy due to the restored Ag electrode induces recovery of the fill factor. The diffused I− ions react with the PCBM molecules, resulting in a quasi n‐doping effect of PCBM. Upon electrode exchange, the reversible interaction between the iodine ions and PCBM causes current density variation. The disorder model for the open‐circuit voltage over a wide range of temperatures explains the open‐circuit voltage increase at every electrode exchange. Finally, the degradation mechanism of the inverted perovskite solar cell over 1000 h is described under the proposed recombination system.

Fine-tuning of electronic properties in donor–acceptor conjugated polymers based on oligothiophenes

A novel series of donor–acceptor conjugated polymers having oligothiophenes with well-defined structures were synthesized and their optical, electrochemical, and photovoltaic properties were investigated. It was found that the absorption bands of polymers were red-shifted with increasing number of ethylenedioxy groups added to each oligothiophene unit and that their band edges reached over 1000 nm. The systematical fine-tuning of the electronic properties was achieved using the chemical structures of oligothiophene units. Photovoltaic cells based on polymer/(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) exhibited power conversion efficiencies in the range from 0.004 to 1.10%, reflecting the electronic properties of the polymers.

Molecular complexation between PCBM and porphyrazine in solution: A case study of non-covalent interaction

The present investigations report the non-covalent interaction of a fullerene derivative, namely, [6,6]-phenyl C71 butyric acid methyl ester (PC70BM) with 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (1) and zinc-2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (2) in toluene and also in mixed solvent comprising toluene and 1,2-dichlorobenzene (volume:volume=3:2). Complex formation by steady state fluorescence studies reveal high value of binding constant (K) for both PC70BM-1 and PC70BM-2 systems in toluene, i.e., KPCBM-1=10,820dm3·mol−1 and KPCBM-2=9655dm3·mol−1, and very good selectivity of binding for 1 as a result of change in solvent polarity, viz., KPC70BM-1 (Toluene)/KPC70BM-1 (Mixed Solvent) ~3.0. Due to solvophobic effect, the selectivity in binding for 2 in two different solvents, i.e., KPC70BM-2 (Toluene)/KPC70BM-2 (Mixed Solvent) estimated to be ~1.0. Lifetime measurements establish that static quenching mechanism is operative behind the photoexcited decay of 1⁎ (and/2⁎) in presence of PC70BM both in toluene and in mixed solvent. However, in mixed solvent, PC70BM-1 system is found to exhibit much higher value of magnitude of rate constant of charge-separation (i.e., kCSs(PC70BM-1)=2.97×107s−1) and kCSs(PC70BM-2)=5.60×106s−1) and quantum yield of charge-separation (ϕCS(PC70BM-1)=0.070) compared to PC70BM-2 system (ϕCS(PC70BM-1)=0.015). Ab initio calculations in vacuo predict the geometric structures of PC70BM-1 and PC70BM-2 systems and provide very good support in favour of charge-separation in former system in terms of multipole moment calculations.

New n-Type Solution Processable All Conjugated Polymer Network: Synthesis, Optoelectronic Characterization, and Application in Organic Solar Cells.

The efficient synthesis of a new solution-processable n-type conjugated polymer network (PNT1) is reported through palladium-catalyzed Stille cross-coupling reaction conditions following the A3 + B2 synthetic approach. A benzo[1,2-b:3,4-b':5,6-b″]trithiophene derivative is used as the A3 knot and an alkyl functionalized naphthalenediimide is utilized as the B2 linker. The thermal, optical, and electrochemical properties are examined in detail, showing high thermal stability, absorbance in the visible part of the solar spectrum, and reversible reduction characteristics similar to those of the fullerene derivative [6,6]-phenyl-C71 -butyric acid methyl ester (PC71 BM). PNT1 is employed as the electron acceptor in solution-processed bulk heterojunction organic solar cells, demonstrating the potential of this new type of materials for optoelectronic applications.

Synthesis and elastase inhibition activities of novel aryl, substituted aryl, and heteroaryl oxime ester derivatives.

Fifteen novel aryl, substituted aryl and heteroaryl γ-hydroxy- (2a-e), γ-methoxyimino- (3a-e), and γ-benzyloxyimino- (4a-e) butyric acid methyl esters were investigated for their enzyme inhibition, and the synthesis of 10 compounds (3a-e, 4a-e) is given in this study. The other five compounds (2a-e) were synthesized before in another study. Compounds 3a-e and 4a-e were synthesized in this work as original compounds and characterized by 1 H and 13 C NMR, IR, mass, and elemental analyses. Their (E/Z)-isomerisation ratios were analyzed by 1 H and 13 C NMR. All of them are of pure (E)-configuration. Due to the literature survey, the elastase inhibition activity was not studied for these compounds. Elastase inhibition ability was investigated in this work for five γ-hydroxy- (2a-e), five γ-methoxy- (3a-e), and five γ-benzyloxyimino- (4a-e) butyric acid methyl esters. All these 15 compounds showed elastase inhibition activity. Compound 2b was the best one and exhibited a better activity than the standard ursolic acid whereas compound 2a worked like the standard. All these compounds can be novel elastase inhibitor agents in the pharmaceutical and cosmetic industries.

Synergistic Effects of Selenophene and Extended Ladder-Type Donor Units for Efficient Polymer Solar Cells.

Two pairs of polymer donor materials based on indacenodithiophene (IDT) and indacenodithieno[3,2-b]thiophene (IDTT) as the donor units are synthesized. Thiophene or selenophene is introduced as the π-bridge units and electron-deficient fluorine-substituted quinoxaline is used as acceptor unit. Selenophene-containing polymers PIDT-DFQ-Se and PIDTT-DFQ-Se show redshifted absorption and narrower bandgaps. Combined with IDTT donor unit, PIDTT-DFQ-Se shows the highest absorption coefficient. Both the IDTT unit and selenophene unit have positive effects on the hole mobilities, making PIDTT-DFQ-Se the highest one. The best power conversion efficiency of 7.4% is obtained from devices based on PIDTT-DFQ-Se:[6,6]-phenyl C71 butyric acid methyl ester (PC71 BM) with a Jsc of 12.6 mA cm-2 , a Voc of 0.89 V, and a fill factor (FF) of 0.66.

Diblock Copolymer PF-b-PDMAEMA as Effective Cathode Interfacial Material in Polymer Solar Cells.

An alcohol-soluble diblock copolymer poly[2,7-(9,9-dihexylfluorene)]15-block-poly[2-(dimethylamino)ethyl methacrylate]75 (denoted as PF15-b-PDMAEMA75) was employed as the cathode interfacial layer (CIL) in p-i-n polymer solar cells (PSCs). PF15-b-PDMAEMA75 contains a conjugated rigid block and a nonconjugated flexible block grafted with polar amino groups, and it can effectively lower the work function of the Al cathode and decrease the series resistance of the devices. When applied as the CIL in PSCs based on poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexy)carbonyl]thieno[3,4-b]thiophenediyl]]:[6,6]-phenyl C71 butyric acid methyl ester, the champion power conversion efficiency of 8.80% was achieved, which is slightly higher than that of the PSCs using the well-known poly[(9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] as CIL under our experimental conditions, and much better than that of PSCs using Ca as CIL. The improvement of the performance is mainly attributed to the enhanced open-circuit voltage and fill factor. To the best of our knowledge, this is the first time a diblock copolymer has been used as a CIL in PSCs, and this study may provide a novel avenue for the design and synthesis of interfacial materials for high-performance PSCs.

Impact of charge-transfer excitons in regioregular polythiophene on the charge separation at polythiophene-fullerene heterojunctions

This study addresses the mechanism of ultrafast charge separation in regioregular oligothiophene-fullerene assemblies representative of poly-3-hexylthiophene (P3HT)-[6,6]-phenyl-C61 butyric acid methyl ester (PCBM) heterojunctions, with special emphasis on the inclusion of charge transfer excitons in the oligothiophene phase. The formation of polaronic inter-chain charge separated species in highly ordered oligothiophene has been demonstrated in recent experiments and could have a significant impact on the net charge transfer to the fullerene acceptor. The present approach combines a first-principles parametrized multi-site Hamiltonian, based on time-dependent density functional theory calculations, with accurate quantum dynamics simulations using the multi-layer multi-configuration time-dependent Hartree method. Quantum dynamical studies are carried out for up to 182 electronic states and 112 phonon modes. The present analysis follows up on our previous study of (Huix-Rotllant et al 2015 J. Phys. Chem. Lett. 6 1702) and significantly expands the scope of this analysis by including the dynamical role of charge transfer excitons. Our investigation highlights the pronounced mixing of photogenerated Frenkel excitons with charge transfer excitons in the oligothiophene domain, and the opening of new transfer channels due the creation of such charge-separated species. As a result, it turns out that the interfacial donor/acceptor charge transfer state can be largely circumvented due to the presence of charge transfer excitons. However, the latter states in turn act as a trap, such that the free carrier yield observed on ultrafast time scales is tangibly reduced. The present analysis underscores the complexity of the transfer pathways at P3HT-PCBM type junctions.

Microwave exposure as a fast and cost-effective alternative of oxygen plasma treatment of indium-tin oxide electrode for application in organic solar cells

Pre-treatment methods are commonly employed to clean as well as to modify electrode surfaces. Many previous reports suggest that modifying the surface properties of indium tin oxide (ITO) by oxygen plasma treatment is a crucial step for the fabrication of high performance organic solar cells. In this work, we propose a fast and cost-effective microwave exposure step for the modification of the surface properties of ITO anode electrodes used in organic solar cells. It is demonstrated that a short microwave exposure improves the hydrophilicity and reduces the roughness of the ITO surface, as revealed by contact angle and atomic force microscopy (AFM) measurements, respectively, leading to a better quality of the PEDOT:PSS film coated on top of it. Similar results were obtained with the commonly used oxygen plasma treatment of ITO suggesting that microwave exposure is an effective process for modifying the surface properties of ITO with the benefits of low-cost, easy and fast processing. In addition, the influence of the microwave exposure of ITO anode electrode on the performance of an organic solar cell based on the poly(3-hexylthiophene):[6,6]-phenyl C70 butyric acid methyl ester (P3HT:PC70BM) blend is investigated. The 71% efficiency enhancement obtained in the microwave annealed-ITO based device as compared to the device with the as-received ITO was mainly attributed to the improvement in the short circuit current (Jsc) and decreased leakage current caused by the reduced series and the increased shunt resistances and also by the higher charge generation efficiency, and the reduced recombination losses.

The effects of SQ additive on charge carrier transport and recombination in PCDTBT:PC71BM based ternary organic solar cells

The ternary solar cell has been proved as an elegant strategy to realize efficient bulk heterojunction (BHJ) organic solar cells (OSCs) by harvesting a larger range of photons than binary devices. In order to design such an efficient system, the charge carrier transport and recombination in ternary OPVs must be considered. We fabricated various ternary devices by adding squaraine derivatives (SQ-1, SQ-2, SQ-3, SQ-4 and SQ-5) with complementary absorption spectrum in near infrared region as the additional donor material into Poly [[9-(1-octylnonyl)-9H-carbazole-2, 7-diyl]-2, 5-thiophenediyl-2, 1, 3-benzothiadiazole-4, 7-diyl-2, 5-thiophenediyl] (PCDTBT): [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) host binary blend film in this paper. Through the charge carrier mobility and transient photovoltage (TPV) measurements, it is found that the incorporation of 10% SQ-5 with shallower Highest Occupied Molecular Orbital (HOMO) level hinders holes in transferring from SQ to PCDTBT, which leads to unbalanced charge carrier transport, significant charge recombination, and decrease of performance. On the contrary, the performance of ternary devices incorporated with 10% SQ-3 with deeper HOMO energy level is improved by 21% compared with binary devices, which can be attributed to increased photon harvesting and changeless charge carrier characteristics.

Ultra-Low Powered CNT Synaptic Transistor Utilizing Double PI:PCBM Dielectric Layers

We demonstrated a CNT synaptic transistor by integrating 6,6-phenyl-C61 butyric acid methyl ester(PCBM) molecules as charge storage molecules in a polyimide(PI) dielectric layer with carbon nanotubes(CNTs) for the transistor channel. Specifically, we fabricated and compared three different kinds of CNT-based synaptic transistors: a control device with Al2O3/PI, a single PCBM device with Al2O3/PI:PCBM(0.1 wt%), and a double PCBM device with Al2O3/PI:PCBM(0.1 wt%)/PI:PCBM(0.05 wt%). Statistically, essential device parameters such as Off and On currents, On/Off ratio, device yield, and longterm retention stability for the three kinds of transistor devices were extracted and compared. Notably, the double PCBM device exhibited the most excellent memory transistor behavior. Pulse response properties with postsynaptic dynamic current were also evaluated. Among all of the testing devices, double PCBM device consumed such low power for stand-by and its peak current ratio was so large that the postsynaptic current was also reliably and repeatedly generated. Postsynaptic hole currents through the CNT channel can be generated by electrons trapped in the PCBM molecules and last for a relatively short time(~ hundreds of msec). Under one certain testing configuration, the electrons trapped in the PCBM can also be preserved in a nonvolatile manner for a long-term period. Its integrated platform with extremely low stand-by power should pave a promising road toward next-generation neuromorphic systems, which would emulate the brain power of 20W.

Aqueous PCDTBT:PC71 BM Photovoltaic Inks Made by Nanoprecipitation.

The fabrication of organic solar cells from aqueous dispersions of photoactive nanoparticles has recently attracted the interest of the photovoltaic community, since these dispersions offer an eco-friendly solution for the fabrication of solar cells, avoiding the use of toxic solvents. In this work, aqueous dispersions of pure poly[n-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) and [6,6]-phenyl-C71 -butyric acid methyl ester (PC71 BM) nanoparticles, as well as of composite PC71 BM:PCDTBT nanoparticles, are prepared using the nanoprecipitation postpolymerization method. These dispersions are subsequently used to form the active layer of organic photovoltaic cells. Thin films of PC71 BM and PCDTBT are obtained by spray deposition of the nanoparticles' dispersions, and are characterized using a combination of spectroscopic and microscopic techniques. Photovoltaics that incorporate these active layers are fabricated thereafter. The impact of the annealing temperature and of the composition of the active layer on the efficiency of the solar cells is studied.

Electrical and optical modeling of poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester P3HT–PCBM bulk heterojunction solar cells

In this work, we investigate a two-dimensional theoretical model for the photon conversion through an integration of the optical and electrical part of multilayer system in a bulk heterojunction solar cell based on poly(3-hexylthiophene) (P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. The optical properties of the studied structure ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al, such as the exciton generation rate and the electrical field distribution, are predicted at vicinity of the active layer and have been used to solve Poisson and continuity, drift–diffusion equations of the electrical model which characterize the electrical behavior of semiconductor device using finite element method (FEM). The electrical parameters such as power conversion efficiency (PCE), open voltage circuit (V oc), short-circuit current density (J sc) and fill factor (FF) are extracted from the current–voltage (J–V) characteristics under illumination and in dark conditions. Highest external quantum efficiency (IPCE), up to 60%, is obtained around 520 nm, while a power conversion efficiency (PCE) value of 3.62% is found to be in good agreement with the literature results. Integration of such theoretical approach into technological applications dealing with optoelectrical material performance will rapidly provide to the user accurate data outputs required for efficient validation of proof-of-concepts.

Influence of annealing temperature on morphologies and crystallinity of pure and blended diketopyrrolopyrrole-containing oligothiophene thin films

We investigated the variations in solution-processed thin films containing pure diketopyrrolopyrrole-containing oligothiophene (SMDPPEH) or SMDPPEH blended with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) under the different annealing temperatures. The optical properties, microstructures, and surface morphologies of the two types of thin films were characterized with UV–vis absorption spectra, grazing incidence X-ray diffraction (GIXRD), and atomic force microscopy (AFM). SMDPPEH thin film annealed at 100°C exhibited a blue-shift of absorption maximum (λmax) peaks. GIXRD results of two types of films showed that (100) diffraction peak intensities were enhanced by increasing annealing temperatures and their shapes were changed from dot to arc when annealing temperatures were beyond 100°C. AFM results showed that the films grain sizes increased as annealing temperature increased. AFM results also showed obvious large-size phase segregation in the films as annealing temperature increased to 125°C. These results indicated that the crystallinity improved with increasing annealing temperature and a phase transition occurred in SMDPPEH films at the annealing temperature of 100°C. This phase transition may lead to maximum device performance.

High‐Performance Wide Bandgap Copolymers Using an EDOT Modified Benzodithiophene Donor Block with 10.11% Efficiency

AbstractNewly developed benzo[1,2‐b:4,5‐b′]dithiophene (BDT) block with 3,4‐ethylenedioxythiophene (EDOT) side chains is first employed to build efficient photovoltaic copolymers. The resulting copolymers, PBDTEDOT‐BT and PBDTEDOTFBT, have a large bandgap more than 1.80 eV, which is attributed to the increased steric hindrance between the BDT and EDOT skeletons. Both copolymers possess the satisfied absorptions, low‐lying highest occupied molecular orbital (HOMO) levels and high crystallinity. Using the fluorination strategy, PBDTEDOT‐FBT exhibits a wider and stronger absorption and a deeper HOMO level than those of PBDTEDOT‐BT. PBDTEDOT‐FBT:[6,6]‐Phenyl C71 butyric acid methyl ester (PC71BM) blend also shows the higher hole mobility and better surface morphology compared with the PBDTEDOTBT:PC71BM blend. Combination of above advantages, PBDTEDOT‐FBT devices exhibit much higher power conversion efficiency (PCE) of 10.11%, with an improved open circuit voltage (Voc) of 0.86 V, short circuit current densities (Jsc) of 16.01 mA cm−2, and fill factor (FF) of 72.6%. This work not only provides a newly efficient candidate of BDT donor block modified with EDOT conjugated side chains, but also achieves high‐performance large bandgap copolymers for polymer solar cells (PSCs) via the synergistic effect of fluorination and side chain engineering strategies.

Small Molecules Derived from Thieno[3,4-c]pyrrole-4,6-dione (TPD) and Their Use in Solution Processed Organic Solar Cells.

In this work, microwave synthesis, chemical, optical and electrochemical characterization of three small organic molecules, TPA-TPD, TPA-PT-TPD and TPA-TT-TPD with donor-acceptor structure and their use in organic photovoltaic cells are reported. For the synthesis, 5-(2-ethylhexyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione was used as electron withdrawing fragment while the triphenylamine was used as electron donating fragment. Molecular electronic geometry and electronic distribution density were established by density functional theory (DFT) calculations and confirmed by optical and chemical characterization. These molecules were employed as electron-donors in the active layer for manufacturing bulk heterojunction organic solar cells, where [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) was used as electron-acceptor. As cathode, Field′s metal (FM), an eutectic alloy (Bi/In/Sn: 32.5%, 51%, and 16.5%, respectively) with a melting point above 62 °C, was easily deposited by drop casting under vacuum-free process and at air atmosphere. Prepared devices based on TPA-TPD:PC71BM (1:4 w/w ratio) presented a large VOC = 0.97 V, with JSC = 7.9 mA/cm2, a FF = 0.34, then, a power conversion efficiency (PCE) of 2.6%.

Functionalized 2D-MoS2-Incorporated Polymer Ternary Solar Cells: Role of Nanosheet-Induced Long-Range Ordering of Polymer Chains on Charge Transport.

In this paper, we demonstrated the enhancement in power conversion efficiency (PCE) of solar cells based on poly(3-hexylthiophene-2,5-diyl) (P3HT)/[6,6]-phenyl C71 butyric acid methyl ester (PC71BM) by incorporation of functionalized 2D-MoS2 nanosheets (NSs) as an additional charge-transporting material. The enhancement in PCE of ternary solar cells arises due to the synergic enhancement in exciton dissociation and the improvement in mobility of both electrons and holes through the active layer of the solar cells. The improved hole mobility is attributed to the formation of the long-range ordered nanofibrillar structure of polymer phases and improved crystallinity in the presence of 2D-MoS2 NSs. The improved electron mobility arises due to the highly conducting 2D network of MoS2 NSs which provides additional electron transport channels within the active layer. The nanosheet-incorporated ternary blend solar cells exhibit 32% enhancement in PCE relative to the binary blend P3HT/PC71BM.

High performance photomultiplication perovskite photodetectors with PC60BM and NPB as the interlayers

Abstract Organic-inorganic hybrid perovskites have attracted more attention as successful light harvesting materials for solution-processed semiconductors and exhibit remarkable optoelectronic properties. Here photomultiplication-type photodetectors based on perovskite CH 3 NH 3 PbI 3 are demonstrated. By introducing suitable interlayers at the CH 3 NH 3 PbI 3 /electrode interfaces, the performance of the photodetector is significantly improved. The optimized device with a N ,N′-di(naphthalene-1-yl)- N ,N′-diphenylbenzidine anode interface layer and [6,6]-phenyl-C 60 -butyric acidmethyl ester cathode interface layer shows a broadband response with a high photocurrent gain of about 177 and a high detectivity of 4.6 × 10 13 Jones, which are higher than the reference device. Besides, the response speed of the device is also increased. The improvement is attributed to the improved charge carrier collection efficiency and suppressed dark current of the device.