Enhanced Near-infrared Absorption Research Articles

Acceptor-donor-acceptor type organic photothermal agents with enhanced NIR absorption and photothermal conversion effect for cancer photothermal therapy

Numerous photothermal agents (PTAs) require high-intensity and long-duration laser excitation for photothermal therapy (PTT), resulting in light damage to healthy skin and tissue as well as limiting their biomedical applications. Integrating desirable near-infrared (NIR) absorption and high photothermal conversion efficiency (PCE) into a single small-molecule PTA is an important prerequisite for realizing efficient PTT, but is a serious challenge. Herein, through molecular engineering strategy, an acceptor-donor-acceptor (A-D-A) type PTA (ADA3) was readily developed for 808 nm laser-driving photothermal imaging and PTT of tumor. Theoretical calculations and experiment results show molecular engineering strategy is significant in regulating the structure and energy gap of PTAs, so as to effectively induce a narrow band gap for NIR absorption and further optimize photothermal properties. ADA3 possesses molar extinction coefficient of 3.1 × 104 M−1 cm−1 at 808 nm, followed being assembled into nanoparticles, ADA3-NPs show high PCE of 80.3%. In vivo experiments indicate that ADA3-NPs have excellent antitumor capability under one-time, low-intensity and short-duration (808 nm, 330 mW/cm2, 3 min) laser irradiation. Therefore, this work definitely exemplifies the enormous potential of molecular engineering strategy and provides an effective method for developing small-molecule PTAs.

Dithienopyran-based narrow-bandgap donor polymers: Unveiling the potential for semitransparent organic solar cells with enhanced NIR absorption

Semitransparent organic solar cells (ST-OSCs) have recently received considerable attention in the field of photovoltaics owing to their great potential in applications such as building-integrated photovoltaics, self-powered greenhouses, and vehicle coatings. Because the near-infrared (NIR) region is an invisible region whose photon content is higher than that of the visible region, it is preferable to apply photoactive materials with narrow bandgaps in ST-OSCs. Tremendous efforts have been made to develop narrow-bandgap non-fullerene acceptors, however, donor polymers with NIR absorption ability for efficient ST-OSCs have rarely been reported. In this study, two novel narrow-bandgap donor polymers, PDTP-TBT and PDTTP-TBT, are designed and synthesized. Both polymers exhibit strong NIR absorption and high transmittance in the visible region, suggesting their potential for use in ST-OSCs. An opaque OSC with a PDTTP-TBT-based photoactive layer achieves a higher power conversion efficiency (PCE) of 8.87% than a PDTP-TBT-based OSC (PCE of 3.65%) due to its better charge transport characteristics. Furthermore, an ST-OSC using PDTTP-TBT-based blend film exhibits a PCE of 6.72%, average visible transmittance of 43.9%, and light utilization efficiency of 2.95%.

Collagen-induced assembly of adenosine monophosphate-modified gold nanoparticles for photothermal cancer therapy

BackgroundPhotothermal therapy (PTT) has become an attractive approach for cancer treatment due to its merits of minimal invasiveness, location selectivity, and suitability for various cancer types. In PTT, photosensitizers are usually adopted to convert light to heat at tumor site, thereby generating heat-induced necroptosis or apoptosis. Therefore, the performance of photosensitizer (e.g., photothermal conversion efficiency (PCE), surface property, tumor accumulation and retention, etc.) determines the clinical manifestation of PTT. Currently, the poor tumor retention and potential long-term toxicity are two main obstacles for developing efficient photosensitizers. To address these issues, we have developed an in vivo tumor microenvironment stimuli-responsive self-assembled photosensitizer, which consists of a biomolecule, adenosine monophosphate (AMP) modified gold nanoparticles (AAu NPs), to enhance the accumulation and retention within tumor tissue for efficient PTT.ResultsThe obtained AAu NPs with a hydrodynamic diameter of 9.12 ± 0.82 nm have excellent colloidal stability in aqueous solution. No sediments can be observed in the AAu NPs aqueous phase even after several months. The temperature of AAu aqueous suspension is elevated to 53.0 ℃ within 8 min at a low particle concentration of 80 μg/mL. A high PCE of 62.8% is obtained for AAu NPs based on the temperature change curves. The near-infrared (NIR) absorption and PCE of AAu NPs are enhanced compared to the surfactant-free Au NPs, enabling excellent photothermal cell-killing in vitro. When the AAu NPs arrive at the tumor tissue, they quickly form large aggregates via a collagen-induced assembly, leading to enhanced NIR absorption and improved tumor accumulation and retention, which enables a high PTT efficacy in vivo at a low photosensitizer dose of 40 μg and a low laser power density of 1.91 W/cm2.ConclusionsA collagen-induced self-assembled gold photosensitizer for efficient PTT has been synthesized based on a biomolecule, AMP modification method. The synthesized AAu NPs with high PTT efficacy, superior biosafety and fast excretion from the body is an effective therapeutic agent in photothermal cancer therapy.

Covalent Assembly of Clickable Carbon Nanodots in Water-in-Oil Emulsion for Enhanced Antibacterial Photothermal Therapy

One challenge in the field of photothermal therapy (PTT) is to design an assembly of carbon nanodots (CNDs) with enhanced light absorption in the near-infrared (NIR) spectral region and improved photothermal conversion efficiency. Herein, a type of CND assembly was fabricated using a covalent click reaction in a water-in-oil emulsion system (abbreviated as W/O assembly), providing excellent stability, controllable size distributions, enhanced NIR absorption, and improved applications in photothermal imaging (PTI), photoacoustic imaging (PAI), and PTT. A mechanism based on energy dissipation was proposed in detail to explain the changes in photophysical properties before and after CND assembly. In addition, an outstanding antibacterial effect was also observed during the in vitro phototherapy of drug-resistant pathogens. Importantly, the results of in vivo infection assays further verified satisfying photokilling effect toward drug-resistant bacteria and excellent biosafety to normal cells and tissues. Given the benefits of the covalent CND assembly developed in this work, it might have potential applications in the following aspects: (1) strategy of the controllable covalent assembly could be extended to other nanosystems and (2) in situ CND assembly could be built at disease sites based on microenvironment-triggered bioorthogonal click reactions, improving targeting performance and reducing the side effects of PTT.

Surface-Functionalized NdVO4:Gd3+ Nanoplates as Active Agents for Near-Infrared-Light-Triggered and Multimodal-Imaging-Guided Photothermal Therapy.

Development of nanotheranostic agents with near-infrared (NIR) absorption offers an effective tool for fighting malignant diseases. Lanthanide ion neodymium (Nd3+)-based nanomaterials, due to the maximum absorption at around 800 nm and unique optical properties, have caught great attention as potential agents for simultaneous cancer diagnosis and therapy. Herein, we employed an active nanoplatform based on gadolinium-ion-doped NdVO4 nanoplates (NdVO4:Gd3+ NPs) for multiple-imaging-assisted photothermal therapy. These NPs exhibited enhanced NIR absorption and excellent biocompatibility after being grafted with polydopamine (pDA) and bovine serum albumin (BSA) layers on their surface. Upon expose to an 808 nm laser, these resulting NPs were able to trigger hyperthermia rapidly and cause photo-destruction of cancer cells. In a xenograft tumor model, tumor growth was also significantly inhibited by these photothermal agents under NIR laser irradiation. Owing to the multicomponent nanostructures, we demonstrated these nanoagents as being novel contrast agents for in vivo magnetic resonance (MR) imaging, X-ray computed tomography (CT), photoacoustic (PA) imaging, and second biological window fluorescent imaging of tumor models. Thus, we believe that this new kind of nanotherapeutic will benefit the development of emerging nanosystems for biological imaging and cancer therapy.

Near-Infrared Light-Boosted Photodynamic-Immunotherapy based on sulfonated Metal-Organic framework nanospindle

Photoactive metal–organic frameworks have achieved great success in the photodynamic therapy (PDT). However, poor therapeutic effect under near-infrared (NIR) irradiation becomes a big changllege for the fully eradication of tumors by using photodynamic MOFs. Herein, a spindle-shaped PCN-222-SO3H (PCN-SU) with the enhanced NIR absorption was synthesized by the sulfonating reaction. After sulfonation, the strong intramolecular hydrogen bonds between the introduced sulfonic anions and TCPP ligands could induce the distortion of porphyrin rings. This distortion leads to the lower energy gap of HOMO and LOMO, thereby increasing the absorption in the near-infrared region. Comparing with PCN-222, great improvements of photoactive performances in PCN-SU result in the boosting generation of singlet oxygen under NIR irradiation. Furthermore, PCN-SU gives high efficiency to trigger the immunogenic cell death (ICD) and also to stimulate the maturation of dendritic cells than that of prototype PCN-222. The combination of immune checkpoint inhibitors (anti-PD-1) with the photodynamic PCN-SU largely enhances the infiltration of cytotoxic T cells in the tumor site under NIR irradiation, and thus to obtain the tumor suppression of 99.6 % in vivo. This new sulfonating strategy provides a new idea for enhancing the photoactivity of the porphyrin-based delivery system, which is beneficial to the improvement of PDT and related combined treatments.

Core/shell structural ultra-small gold and amyloid peptide nanocomposites with effective bacterial surface adherence and enhanced antibacterial photothermal ablation

The exploration of ultra-small gold nanoparticles (Au NPs) (<5 ​nm) based photothermal nanoagent is important for antibacterial photothermal therapy due to their high biosafety. However, the ultra-small Au NPs usually have low absorption in near infrared (NIR) region, presenting poor NIR-based photothermal conversion. In the present work, a novel core/shell structural gold and amyloid peptide Aβ25-35 nanocomposites (Au@Aβ NCs) were constructed with ultra-small Au NPs (ca. 4.0 ​nm) as the core and Aβ25-35 oligomer as the shell (ca. 3 ​nm thickness) through the facile peptide templated chemical reduction method. The Au@Aβ NCs display enhanced NIR absorption and photothermal conversion efficiency as compared to pure Au NPs due to the extinction of Aβ shell. In addition, the Au@Aβ NCs can strongly adhere to the bacterial surfaces and aggregate together by virtue of the intrinsic self-assembly property of amyloid peptide, which facilitates the local photothermal ablation of bacteria. Consequently, the Au@Aβ NCs can fast and completely kill the pathogenic bacteria under NIR laser irradiation. This work provides an alternative strategy to prepare highly efficient ultra-small Au NPs based photothermal nanoagent for enhancing the antibacterial photothermal ablation.

Biocompatible conjugated porphyrin nanoparticles with photodynamic/photothermal performances in cancer therapy

Phototherapy has emerged as a promising way to treat cancer with high selectivity and non-invasiveness. With a vision towards solving the safety problems of current inorganic materials, tremendous efforts have been dedicated to search for much safer and more efficient organic nanoagents for cancer phototherapy. Herein, we design and synthesize a new porphyrin compound (TPAPor) by covalent conjugation of porphyrin and triphenylamine. The typical donor-acceptor-donor (D-A-D) structure of TPAPor facilitates the red-shift of absorption to the near-infrared (NIR) region. Subsequently, the amphiphilic organic molecule is self-assembled into nanoparticles (TPAPor NPs) with homogeneous size (about 80 nm), enhanced NIR absorption and excellent biocompatibility. TPAPor NPs display low singlet oxygen (1O2) generation and excellent photothermal conversion efficiency (55.7%) under irradiation of a single NIR laser (690 nm). Moreover, TPAPor NPs could ablate the HeLa cells by NIR laser-induced ROS and heat generation, with the half maximal inhibitory concentrations (IC50) about 18.3 μg/mL. This study indicates TPAPor NPs are promising nanoagents for cancer therapy through photothermal/photodynamic combination manner.

Laser ablation in liquids for the assembly of Se@Au chain-oligomers with long-term stability for photothermal inhibition of tumor cells

For the potential use of Au nanoparticles (NPs) in photothermal therapy, it is important and effective to achieve the uniaxial assembly of Au NPs to allow enhanced absorption in the near infrared (NIR) region. Herein, we first presented the construction of amorphous selenium encapsulated gold (Se@Au) chain-oligomers by successive laser ablation of Au and Se targets in sodium chloride solution without other toxic precursors, stabilizers, or templating molecules. Se@Au chain-oligomers showed evidently enhanced NIR absorption and excellent photothermal transduction efficiency (η), which was higher than 47% at 808 nm. After being stored for 1 year, the Se@Au colloids still exhibited outstanding photothermal performance. The cytotoxicity assay demonstrated that there is negligible toxicity of Se@Au chain-oligomers in cells, but cell viability declined to only 1% in phototherapeutic experiments that were implemented in vitro. In intracellular Reactive Oxygen Species (ROS) generation measurements, Se@Au chain-oligomers could trigger a 35.9% increment of ROS upon laser irradiation. The possible synergetic effects between the anticancer function of Se and photothermal behaviors of Se@Au oligomers were intended to increase ROS level in cells. Therefore, such designed Se@Au chain-oligomers of high stability exhibit promising potential for their use as in vivo photothermal therapeutic agents.

A hierarchical assembly strategy for near-infrared photothermal conversion: unconventional heterogeneous metalla[2]catenanes.

Herein, we report a hierarchical assembly strategy for constructing heterogeneous half-sandwich organometallic D–A (D = π-donor, A = π-acceptor) interlocked structures, and their application in near-infrared (NIR) photothermal conversion. Thienothiophene and diketopyrrolopyrrole groups were selected as the D and A units, leading to two homogeneous metalla[2]catenanes with D–D–D–D and A–A–A–A stacks, respectively. By the ordered secondary assembly of homogeneous metalla[2]catenanes, two unprecedented heterogeneous D–A metalla[2]catenanes comprising an unusual mixed D–A–D–D and unconventional D–A–A–A stacks were realized by the combination of multiple noncovalent interactions, as all demonstrated by a detailed X-ray crystallographic study. Benefiting from the mixed D–A stacking modes, NIR absorption of heterogeneous D–A metalla[2]catenanes is significantly enhanced in contrast to homogeneous metalla[2]catenanes. Thanks to the enhanced NIR absorption and the fluorescence quenching effect from half-sandwich organometallic fragments, heterogeneous D–A metalla[2]catenanes displayed high-performance NIR photothermal conversion properties (η = 27.3%).

Inorganic Nanoshell-Stabilized Liquid Metal for Targeted Photonanomedicine in NIR-II Biowindow.

Gallium and gallium-based alloys, typical types of liquid metals with unique physiochemical properties, are emerging as a next generation of functional materials in versatile biomedical applications. However, the exploration of their biomedical performance is currently insufficient, and their intrinsic low oxidative resistance is a key factor blocking their further clinical translation. Herein, we report on the surface engineering of liquid metal-based nanoplatforms by an inorganic silica nanoshell based on a novel but facile sonochemical synthesis for highly efficient, targeted, and near-infrared (NIR)-triggered photothermal tumor hyperthermia in the NIR-II biowindow. The inorganic silica-shell engineering of liquid metal significantly enhances the photothermal performance of the liquid metal core as reflected by enhanced NIR absorption, improved photothermal stability by oxidation protection, and abundant surface chemistry for surface-targeted engineering to achieve enhanced tumor accumulation. Systematic in vitro cell-level evaluation and in vivo tumor xenograft assessment demonstrate that (Arg-Gly-Asp) RGD-targeted and silica-coated nanoscale liquid metal substantially induces phototriggered cancer-cell death and photothermal tumor eradication, accompanied by high in vivo biocompatibility and easy excretion out of the body. This work provides the first paradigm for surface-inorganic engineering of liquidmetal-based nanoplatforms for achieving multiple desirable therapeutic performances, especially for combating cancer.

Ultrasound assisted one-step synthesis of Au@Pt dendritic nanoparticles with enhanced NIR absorption for photothermal cancer therapy.

Near-infrared (NIR) light-mediated non-invasive photothermal therapy (PTT) has attracted considerable attention for cancer treatment. Strong optical absorption located in the NIR region and high performance in converting light to heat should be emphasized for the development of ideal photothermal agents. In this report, Au@Pt bimetallic nanoparticles (Au@Pt NPs) with dendritic structure were synthesized through an ultrasound assisted one-step method in aqueous solution. The absorption of Au@Pt NPs at 808 nm was obviously enhanced compared to that of Au NPs and could be easily manipulated via the amount of Pt NPs. Au@Pt NPs exhibited excellent photostability with a photothermal conversion efficiency of 44.2%, which is significantly higher than those in most reported studies. Au@Pt NPs with thiol PEG functionalization presented improved cellular killing capacity upon NIR laser irradiation. Moreover, the potential application of Au@Pt NPs was also investigated in xenograft tumor mouse model. Overall, the remarkable therapeutic characteristics of PEGylated Au@Pt NPs provide them with great potential for future cancer treatment.

Laser-Activated Bioprobes with High Photothermal Conversion Efficiency for Sensitive Photoacoustic/Ultrasound Imaging and Photothermal Sensing.

Laser-activated bioprobes with high photothermal conversion efficiency (IRPDA@PFH NDs) based on biocompatible IR-780 doped polydopamine perfluorocarbon nanodroplets (NDs) were developed. When protected by gelatin microspheres, their near-spherical morphologies can be easily observed with transmission electron microscope. Doping IR-780 (3 w/w % of added dopamine hydrochloride) can significantly enhance near-infrared (NIR) absorption and photothermal conversion efficiency to 57.7%. The enhanced NIR absorption and nonradiative relaxation are preferred to stronger photoacoustic (PA) signals and higher PA imaging definition; ultrasound (US) signals also increase more than 2.5 times because of easier phase change of NDs. These bioprobes had sensitive PA/US imaging capability with highly effective substitute utilizations, in which polydopamine was used either as a PA contrast or a photothermal agent. Perfluorocarbon can be used as an US contrast agent and temperature indicator. More importantly, the gray value increments of US increase with temperature in a general range from 35 to 55 °C. Especially, an approximate linear increasing of gray value in the optimized photothermal therapy (PTT) range from 35°C to 50°C could be used for the temperature monitoring and control of PTT. During PTT, the heated regions and the extent of photothermal heating can be visualized by US imaging. These findings indicate their great potential for biosensing and PTT monitoring.

Control of Crystallinity in PbPc:C60 Blend Film and Application for Inverted Near-Infrared Organic Photodetector.

Inverted near-infrared (NIR) organic photodetectors (OPDs) are required to combine the OPDs with an n-channel silicon-based integrated circuit. NIR absorption in the 930-960 nm range is important because the intensity of solar irradiation is low in this wavelength regime. Here, we controlled the crystallinity of lead(II) phthalocyanine (PbPc) in a PbPc:C60 blendfilmto obtain NIR absorption. To form a triclinic phase responsible for NIR light absorption, a substrate was heated during fabrication and C60 was used as a templating layer, as well as an electron extraction layer, for an inverted structure. NIR absorption near 950 nm was enhanced, and the structural properties of the film changed dramatically. The OPD with enhanced NIR absorption exhibited a responsivity of 244 mA/W and an external quantum efficiency of 31.1% at a reverse bias of -3 V and 970 nm. The OPD detectivity also increased to 9.01 × 1012 and 1.36 × 1011 cm Hz1/2/W under a zero bias and a reverse bias of -3 V, respectively.

Near-infrared photodetector achieved by chemically-exfoliated multilayered MoS2 flakes

A near-infrared (NIR) photodetector built from chemically exfoliated multilayer MoS2 films was investigated. Devices that are photoresponsive to wavelengths up to 1550 nm were fabricated using 25-nm-thick MoS2 films. To the best of our knowledge, this is the first time such a detector was produced using chemical exfoliation. As the thickness was increased to 25 nm, the MoS2 flakes formed a nearly or fully continuous film with a 2H-dominant phase, and also exhibited enhanced NIR absorption up to 1550 nm. We conjecture that the defects formed during chemical exfoliation affect the intrinsic bandgap of MoS2, extending its spectral absorption range into the NIR range. Moreover, the responsivity of the device was enhanced by introducing plasmonic Ag nanocrystals.

Photothermally Controlled MHC Class I Restricted CD8+ T-Cell Responses Elicited by Hyaluronic Acid Decorated Gold Nanoparticles as a Vaccine for Cancer Immunotherapy.

Cancer vaccines aim to induce a strong major histocompatibility complex class I (MHC-I)-restricted CD8+ cytotoxic T-cell response, which is an important prerequisite for successful cancer immunotherapy. Herein, a hyaluronic acid (HA) and antigen (ovalbumin, OVA)-decorated gold nanoparticle (AuNPs)-based (HA-OVA-AuNPs) vaccine is developed for photothermally controlled cytosolic antigen delivery using near-infrared (NIR) irradiation and is found to induce antigen-specific CD8+ T-cell responses. Chemical binding of thiolated HA and OVA to AuNPs facilitates antigen uptake of dendritic cells via receptor-mediated endocytosis. HA-OVA-AuNPs exhibit enhanced NIR absorption and thermal energy translation. Cytosolic antigen delivery is then permitted through the photothermally controlled process of local heat-mediated endo/lysosome disruption by laser irradiation along with reactive oxygen species generation, which helps to augment proteasome activity and downstream MHC I antigen presentation. Consequently, the HA-OVA-AuNPs nanovaccine can effectively evoke a potent anticancer immune response in mice under laser irradiation. This NIR-responsive nanovaccine is promising as a potent vaccination method for improving cancer vaccine efficacy.

A New Green Titania with Enhanced NIR Absorption for Mitochondria-Targeted Cancer Therapy.

A new kind of green titania (G-TiO2-x) with obvious green color was facilely synthesized from black titania (B-TiO2-x) through subsequently strong ultrasonication. Comparatively, this stable G-TiO2-x shows much enhanced near infrared (NIR) absorption, especially around 920 nm, which can be ascribed to the obvious change of TiO2-x lattice order owing to the effect of ultrasonication. This feature enables G-TiO2-x to be stimulated with 980 nm laser in the combined photodynamic therapy (PDT) and photothermal therapy (PTT), which is greatly beneficial for improving tissue penetration depth. Furthermore, since mitochondria are preferred subcellular organelles for PDT/PTT, G-TiO2-x was further designed to conjugate with triphenylphosphonium (TPP) ligand for mitochondria-targeted PDT/PTT to obtain precise cancer treatment. Attributing to the high mitochondria-targeting efficiency and simultaneously synergistic PDT/PTT, high phototherapeutic efficacy and safety with a much lower laser power density (980 nm, 0.72 W cm-2) and low materials dosage were achieved both in vitro and in vivo. In addition, negligible toxicity was found, indicating high biocompatibility. This novel G-TiO2-x could provide new strategies for future precise minimal/non-invasive tumor treatment.

Plasmonic Nanowire‐Enhanced Upconversion Luminescence for Anticounterfeit Devices

A novel, efficient, cost‐effective, and high‐level security performance anticounterfeit device achieved by plasmonic‐enhanced upconversion luminescence (UCL) is demonstrated. The plasmonic architecture consists of the randomly dispersed Ag nanowires (AgNWs) network, upconversion nanoparticles (UCNPs) monolayer, and metal film, in which the UCL is enhanced by a few tens, compared to reference sample, becuase the plasmonic modes lead to the concentration of the incident near infrared (NIR) light in the UCNPs monolayer. In the configuration, both the localized surface plasmons (LSPs) around the metallic nanostructures and gap plasmon polaritons (GPPs) confined in the UCNPs monolayer, significantly contribute to the UCL enhancement. The UCL enhancement mechanism resulting from enhanced NIR absorption, boosted internal quantum process, and formation of strong plasmonic hot spots in the plasmonic architecture is analyzed theoretically and numerically. More interestingly, a proof‐of‐concept anticounterfeit device using the plasmonic‐enhanced UCL is proposed, through which a nonreusable and high‐level cost‐effective security device protecting the genuine products is realized.

Theoretical investigation of porphyrin-based photosensitizers with enhanced NIR absorption

Porphyrins are compounds which are fundamental for designing many photosensitizers assigned for use in photodynamic therapy (PDT). However, photosensitizers available on the drug market are not ideal for use in PDT among others because of their low absorption in the wavelength range optimal for tissue penetration, i.e. the near-infrared (NIR) spectral region. In the present study the density functional theory and its time dependent extension calculations have been used to design new porphyrin-based photosensitizers with absorption in the therapeutic window of PDT of 700-800 nm. Theoretical investigation of four different derivatives of the 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (p-THPP) revealed specific 'bridge' configurations which have a significant influence on absorption spectra. The results of the present study may be a useful starting point for future design of porphyrin derivatives as improved photosensitizers.

Structural Evolution of Evaporated Lead Phthalocyanine Thin Films for Near-Infrared Sensitive Solar Cells

In this work, we focus on the deposition conditions as a means to control the structural evolution of lead phthalocyanine (PbPc) films in order to promote the triclinic structure, thereby inducing a shift in the absorption spectrum toward the near-infrared (NIR). Absorption spectra of PbPc films exhibit an enhanced NIR absorption peak at a wavelength of λ = 900 nm upon (i) increasing film thickness, (ii) increasing substrate temperature, or (iii) decreasing evaporation rate. X-ray diffraction measurements correlate the enhancement of the NIR absorption peak with an improved crystallinity and increased average volume of triclinic domains in the mixed monoclinic−triclinic films. As the surface structure of 10 and 60 nm thick films differ, this implies an asymmetric layer structure with a semicrystalline monoclinic film close to the substrate, evolving to a predominantly triclinic structure in the upper part of the film. We have demonstrated the use of structural control of the PbPc layer in a planar heterojunction solar cell with NIR-sensitivity. Decreasing the evaporation rate results in solar cells with significantly enhanced short-circuit current density (JSC), because of the change in absorption in combination with the longer exciton diffusion length that was estimated for donor layers exhibiting a predominantly triclinic structure. Overall, an optimized solar cell yields a power conversion efficiency of 2.6% (2.1% when correcting for the solar spectrum mismatch), and has external quantum efficiencies above 11% from λ = 320−990 nm with a peak value of 34% at λ = 900 nm.