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By employing a self-assembled hole-blocking-layer (HBL), an elegant and broadly applicable architectural design framework is demonstrated to minimize the “performance-stability-cost” gap of the organic photodiodes.

Photodetectors (PDs) based on organic materials exhibit potential advantages such as low-temperature processing, and superior mechanical properties and form factors. They have seen rapid strides toward achieving performance metrics comparable to inorganic counterparts. Here, a simplified device architecture is employed to realize stable and high-performance organic PDs (OPDs) while further easing the device fabrication process. In contrast to the sequential deposition of the hole blocking layer (HBL) and active layer (conventional 'two-step' processing), the proposed strategy forms a self-assembled HBL and active layer in a 'single-step' process. A high-performance UV-Vis-NIR OPD based on the PM6:BTP-eC9 system is demonstrated using this cost-effective processing strategy. The green solvent processed proof-of-concept device exhibits remarkable responsivity of ∼0.5 A W

For organic solar cells (OSCs), the charge generation mechanism and the recombination loss are heavily linked with charge transfer states (CTS). Measuring the energy of CTS (ECT) by the most widely used technique, however, has become challenging for the non-fullerene-based OSCs with a small driving force, resulting in difficulty in the understanding of OSC physics. Herein, we present a study of the PM6:Y6 bulk heterojunction. It is demonstrated that electro-absorption can not only reveal the dipolar nature of Y6 but also resolve the morphology-dependent absorption signal of CTS in the sub-bandgap region. The device with the optimum blending weight ratio shows an ECT of 1.27 eV, which is confirmed by independent measurements. Because of the charge transfer characteristics of Y6, the charge generation at PM6:Y6 interfaces occurs efficiently under a small but non-negligible driving force of 0.14 eV, and the total recombination loss is as low as 0.43 eV.

Perovskite light-emitting diodes (LEDs) show great potential for next-generation lighting and display technology. Despite intensive studies on single-color devices, there are few reports on perovskite-based white LEDs (Pe-WLEDs). Here, an efficient Pe-WLED based on a blue perovskite and an orange phosphorescent emitter is reported for the first time. It is found that using a simple perovskite/phosphor bilayer emitting structure, there is inefficient energy transfer from the blue perovskite to the orange phosphor, leading to low efficiency and a significant color shift with driving voltage. We address this issue by introducing a quantum-well-like charge-confinement structure for enhancing carrier trapping and thus exciton formation in the phosphorescent emitter. As a result, a high external quantum efficiency of 10.81% is obtained. More interestingly, by tuning the dopant concentration of the phosphorescent emitter using this simple device structure, we can controllably get Pe-WLEDs with very stable white light for display applications or tunable color from warm white to daylight for lighting applications.

Due to their low-temperature deposition, high mobility (>10 cm2/V·s), and electrical conductivity, amorphous ionic oxide semiconductors (AIOSs) have received much attention for their applications in flexible and/or organic electro-optical devices. Here, we report on a study of the flexibility of CdO-In2O3 alloy thin films, deposited on a polyethylene terephthalate (PET) substrate by radio frequency magnetron sputtering at room temperature. Cd1-xInxO1+δ alloys with the composition of x > 0.6 are amorphous, exhibiting a high electron mobility of 40-50 cm2/V·s, a low resistivity of ∼3 × 10-4 Ω·cm, and high transmittance over a wide spectral window of 350 to >1600 nm. The flexibility of both crystalline and amorphous Cd1-xInxO1+δ films on the PET substrate was investigated by measuring their electrical resistivity after both compressive and tensile bending with a range of bending radii and repeated bending cycles. Under both compressive and tensile bending with Rb = 16.5 mm, no significant degradation was observed for both the crystalline and amorphous films up to 300 bending cycles. For a smaller bending radius, the amorphous film shows much less electrical degradation than the crystalline films under compressive bending due to less film delamination at the bending sites. On the other hand, for a small bending radius ( 90%. The OSCs fabricated on an amorphous Cd1-xInxO1+δ-coated flexible PET substrate achieve a promising PCE of 12.06%. Our results strongly suggest the technological potentials of amorphous Cd1-xInxO1+δ as a reliable and effective transparent conducting material for flexible and organic optoelectronic devices.

Lead-based halide perovskites (APbX3, where A = organic or inorganic cation, X = Cl, Br, I) are suitable materials for many optoelectronic devices due to their many attractive properties. However, the concern of lead toxicity and the poor ambient and operational stability of the organic cation group greatly limit their practical utilization. Therefore, there has recently been great interest in lead-free, environment-friendly all-inorganic halide perovskites (IHPs). Sb and Sn are common species suggested to replace Pb for Pb-free IHPs. However, the large difference in the melting points of the precursor materials (e.g., CsBr and SbBr3 precursors for Cs3Sb2Br9) makes the chemical vapor deposition (CVD) growth of high-quality Pb-free IHPs a very challenging task. In this work, we developed a two-step CVD method to overcome this challenge and successfully synthesized Pb-free Cs3Sb2Br9 perovskite microplates. Cs3Sb2Br9 microplates ∼25 μm in size with the exciton absorption peak at ∼2.8 eV and a band gap of ∼2.85 eV were obtained. The microplates have a smooth hexagonal morphology and show a large Stokes shift of ∼450 meV and exciton binding energy of ∼200 meV. To demonstrate the applications of these microplates in optoelectronics, simple photoconductive devices were fabricated. These photodetectors exhibit a current on/off ratio of 2.36 × 102, a responsivity of 36.9 mA/W, and a detectivity of 1.0 × 1010 Jones with a fast response of rise and decay time of 61.5 and 24 ms, respectively, upon 450 nm photon irradiation. Finally, the Cs3Sb2Br9 microplates also show good stability in ambient air without encapsulation. These results demonstrate that the 2-step CVD process is an effective approach to synthesize high-quality all-inorganic lead-free Cs3Sb2Br9 perovskite microplates that have the potential for future high-performance optoelectronic device applications.

The transfer of heat energy in organic semiconductors (OSCs) plays an important role in advancing the applications of organic electronics, especially for lifetime issues. However, compared with crystalline inorganic semiconductors, the thermal transport of OSCs is less efficient and a relevant understanding is very limited. In this contribution, we show that the heat conduction of OSCs can be enhanced by blending with a "commodity" insulator (both thermal and electrical). PC

Conventional photodetectors are usually “color blind” and require additional dispersive components or complicated structures to recognize colors. In this work, an organic photodetector (OPD) is designed with a layer of molybdenum(VI) oxide (MoO3) stacked on an organic donor/acceptor charge transfer interface. The band structure of the OPD is designed with multiple charge separation channels that can be activated/deactivated under reverse and forward biases. The combination of a high or low photocurrent under reverse and forward biases determines the colors of the received light, and that forms the heart of “non-color blind” ability to recognize light colors in the OPD. The energy structure and charge collection pathways in the OPD are investigated with biased external quantum efficiency (EQE), ultraviolet photoelectron spectroscopy (UPS) and current density–voltage (J–V) studies. The OPD with the ability of color and wavelength determination demonstrates its potential to recognize colors without using additional components and the dual mode operation enables it to work under different conditions via switching its detection ranges with bias voltages. This design principle can be utilized to fabricate multifunctional devices by simply selecting different donor–acceptor materials according to the desired detection ranges.

While humidity treatment has been employed for enhancing the performance of perovskite solar cells and light-emitting diodes (LEDs), only very limited success has been achieved in quasi-two-dimensional (2D) perovskite LEDs (PeLEDs). Here, for the first time, we demonstrate more than one order of magnitude enhancement of the external quantum efficiency (EQE) and electroluminescence (EL) intensity in blue CsPb(Cl/Br)

Perovskite is emerging as a novel emitter in solution-processed light-emitting diodes (LEDs). In these LEDs, morphology, especially the grain size of perovskite, plays a key role in determining electroluminescence performance. Several studies have shown that sizes of the perovskite grains can be controlled by the contact angle between the perovskite solution and the substrate. In this work, we found that in the quasi-two-dimensional (2D) system, the perovskite grain size can be substantially refined when there are hydrogen bonding between the perovskite's organic spacer and the substrates. In fact, for quasi-2D perovskite, with the presence of such hydrogen bond, its effects on the perovskite grain size overshadow the contact angle's effect. We demonstrated that perovskite with refined grains can form amine- or carbazole-based polymers which can form N···H hydrogen bonding with the perovskite's organic spacer. Using these polymers as hole-transporting layers on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, external quantum efficiency of CsPbBr3-based LEDs can be enhanced from 1.5 to 10.0% without passivation treatment. This work suggests that bonding between perovskite precursors and the substrate can have significant influence on the morphology of the final perovskite grains and their optoelectronic performance.

Due to their low-temperature deposition, high mobility (10 cm

Lead-based halide perovskites (APbX

Electromodulation (EM) spectroscopy, a powerful technique to monitor the changes in polarizability p and dipole moment u of materials upon photo-excitation, can bring direct insight into the excitonic properties of materials. However, extracting Δp and Δu from the electromodulation spectrum relies on fitting with optical absorption of the materials where optical effect in different device geometries might introduce large variation in the extracted values. Here, we demonstrate a systematic electromodulation study with various fitting approaches in both commonly adopted reflection and transmission device architectures. Strikingly, we have found that the previously ascribed continuum state threshold from the deviation between the measured and fitting results is questionable. Such deviation is found to be caused by the overlooked optical interference and electrorefraction effect. A generalized electromodulation model is proposed to incorporate the two effects, and the extracted Δp and Δu have excellent consistency in both reflection and transmission modes in all organic film thicknesses., The development of a generalized electromodulation (EM) spectroscopy model that accurately extracts material parameters for organic electronics remains a challenge. Here, the authors report an EM model that enhances parameter extraction accuracy by accounting for optical interference effects.

The performance of wide-band gap perovskite solar cells has a profound impact on the multijunction tandem device efficiency. However, once bromide (Br–) has been adopted to substitute the iodide (I...

Despite the success of solution processed nickel oxide (s-NiOx) as the hole transporting layer (HTL) in organic solar cells, applying s-NiOx in perovskite solar cells (PVSCs) is not that straight forward. The reported power conversion efficiencies (PCEs) of the s-NiOx based PVSCs span a wide range from 8% to over 20% even with a similar recipe. Here, we report that one of the causes for the performance discrepancy might be the large surface dipole on the s-NiOx surface. We find that the perovskite deposited on the as-prepared sol-gel derived s-NiOx has large number of defects at the s-NiOx/perovskite interface. Based on the in-depth mechanism study with various spectroscopy techniques, we propose that the strong surface dipole of the s-NiOx composite film induces adhesion of perovskite precursor ions on the surface of s-NiOx during the perovskite film formation and creates defects in the perovskite crystals at the interface. Such interfacial dipole-ion attachment has been demonstrated can be dissociated by ultraviolet (UV) light soaking experiment. The high energy of the UV light helps to dissociate the physical dipole-ion attachment and mobilize the ions to accommodate the perovskite defect sites. The defect density of the perovskite film on s-NiOx has been significantly reduced by an amount of 4.1 × 1017 cm−3 after the UV light soaking as evidenced by photothermal deflection spectroscopy (PDS) measurement. By treating the s-NiOx surface with a dipolar molecule n-Butylamine, the surface dipole of the s-NiOx film is efficiently reduced and it significantly reduces the defect density in the perovskite film. As a result, the PVSCs based on the n-Butylamine treated s-NiOx layer have achieved a dramatical enhancement in PCE to 18.9% with decent stability at the maximum power point tracking. It is believed that this work provides insight and strategy to develop highly reproducible PVSCs with solution derived metal oxide as interlayers.

Wide-bandgap perovskites are recently drawing tremendous attention in the community for high-efficiency all-perovskite tandem solar cells. However, the formamidinium (FA+) and methylammonium (MA+) based wide-bandgap mixed halide perovskites suffered from high density of traps and pin-holes, respectively. Fundamental understanding on the crystallization and film formation processes are keys to overcome those challenges but not yet clearly understood. In this study, an in-situ photoluminescence technique was used to investigate the perovskite crystallization during the thermal annealing process. It is found that the crystallization of a mixed halide perovskite with bromide (Br−) and iodine (I−) ions following the Ostward ripening crystal growth. Interestingly, it is found that the initial nucleation reaction is quickly completed in the first few seconds, however, leaving the small crystals with inhomogeneous composition. The different aggregation affinities of such inhomogeneous small crystals provoke the formation of pin-holes during the thermal annealing process. By engineering the precursor solution to control the nucleation rate, the chemical composition of the small crystals has become homogenous. Uniform pin-hole free high Br−composited wide-bandgap MA0.9Cs0.1Pb(I0.6Br0.4)3 perovskite films with bandgap energy of 1.8 eV have been realized. The corresponding photovoltaic devices have achieved an encouraging device efficiency of 15.1% with superb photostability.

The operating lifetime of blue quantum-dot light-emitting diodes (QLED) is currently a short slab for this emerging display technology. To pinpoint the origin of device degradation, here we apply multiple techniques to monitor the electric-field distribution and space-charge accumulation across the multilayered structure before and after lifetime tests. Evident by charge-modulated electro-absorption and capacitance-voltage characteristics, the excited electrons in blue quantum dots (QD) are prone to cross the type II junction between the QD emission layer and the electron-transporting layer (ETL) due to the offset of conduction band minimum, leading to space-charge accumulation and operating-voltage rise in the ETL. Therefore, unlike those very stable red devices, of which the lifetime is primarily limited by the slow degradation of hole-transporting layer, the poor lifetime of blue QLED originates from the fast degradation at the QD-ETL junction. Materials engineering for efficient electron injection is prerequisite for the boost of operating lifetime., Wide application of quantum dot light emitting diodes (QLED) in display technology is hindered by the poor lifetime of the blue QLEDs. Here, the degradation mechanism is shown to originate from space charge accumulation in the electron-transporting layer enabling improvements in blue QLED lifetimes.

Depth-dependent growth of perovskite crystals remains challenging for high-performance perovskite solar cells made by a two-step spin-coating method. Effective morphology engineering approaches that enable depth-independent perovskite crystals growth and facile characterization technique to monitor subtle yet influential accompanying changes are urgently required. Here, a porous and intercrossed PbI2–(CsI)0.15 nanorods scaffold is prepared by integrating CsI incorporation with toluene dripping in ambient air, and the underlying mechanism is uncovered. With this porous scaffold and moisture-assisted thermal annealing, depth-independent growth of FA0.85Cs0.15PbI3 is achieved, as evidenced in the photoluminescent (PL) spectra acquired by exciting the perovskite film from the top and bottom individually. It is of broad interest that PL spectroscopy is demonstrated as a sensitive technique to monitor the depth-dependent growth of perovskite. Moreover, the resulting inverted planar FA0.85Cs0.15PbI3 perovskite s...

Marked progress has been made in organometallic halide perovskite (OHP) solar cells, with their power conversion efficiency reaching up to 24.2% owing to the excellent optoelectronic properties such as high light absorption coefficients, long carrier diffusion lengths, and high carrier mobilities. Among the reported highly efficient devices, most were fabricated in a well-controlled inert environment. However, large-scale manufacturing requires ambient processing, which affects the crystallization process of OHP. Recently, considerable attention has been drawn to developing air-processed OHP solar cells, in terms of scientific understanding of the crystallization process and developing processes compatible with large volume manufacturing. This review article summarizes the recent progress made in air-processed OHP solar cells. Specifically, we focus on (1) the microscopic understanding of the impact of the ambient environment on the crystallization process of OHP composites, (2) the approaches to control the crystallization and morphology of OHP in ambient air, and (3) the fabrication processes to achieve highly efficient air-processed OHP solar cells. Finally, we will discuss the challenges and pathways toward commercialization of low-cost air-processed OHP solar cells.

Charge extraction efficiency is one of the key factors to determine the performance of solar cells, which depends on the electronic properties of the electron and hole transporting layers. Sol–gel derived NiOx as the hole transporting layer (HTL) used in perovskite solar cells (PVSCs) promises both low-cost and high-stability. However, current NiOx based PVSCs have a relatively low fill factor (FF) and device efficiency. Here, we show that using an oxide composite approach by incorporating thermally reduced graphene oxide (rGO) into the NiOx layer (NiOx:rGO) can effectively improve the film conductivity without sacrificing its high work function. The improved charge extraction efficiency reduces the interfacial recombination loss and increases the carrier lifetime in NiOx:rGO based PVSCs, which are evidenced by transient photocurrent and transient photovoltage measurements. The NiOx:rGO based PVSC achieves a promising PCE of 19.1% with a significantly improved FF from 73% to 81% compared to the device using solely NiOx. Moreover, the NiOx:rGO based PVSC shows a decent photo-stability tracked at the maximum-power-point and a long shelf-lifetime with negligible degradation in device performance after 70 days. It is believed that the oxide composite transporting layer would be a promising alternative to further develop highly efficient and stable PVSCs.

Despite the rapid progress in device efficiency of the perovskite solar cells (PVSCs), the origin of commonly observed large variability of device performance from one-step to two-step approaches is still elusive. Herein, the processing windows of perovskite films prepared by one-step and two-step processes have been investigated. We find that both perovskite films prepared by one-step and two-step methods in air are much rougher than that prepared in glovebox. For the one-step method, complete perovskite conversion can be readily achieved both in air and in glovebox, but totally different in surface morphology. For the two-step method, residual PbI2 are remained in perovskite film, particularly with larger amount for the film prepared in air. Both rough surface and incomplete conversion hinder the realization of high quality perovskite film in air. The photovoltaic performances of the PVSCs prepared by one-step and two-step methods in glovebox are systematically compared. The generally observed lower photovoltaic performance of two-step PVSCs is ascribed to the additional trap-assisted recombination process due to larger trap density in the two-step perovskite film. This is confirmed by carrier recombination study using steady state photoluminescence, transient photovoltage and photocurrent measurements. Finally, combining the high work function hole transporting material poly-TPD, and the high-quality one-step perovskite film, a 17.5% high-efficiency PVSCs can be achieved. The results reveal the major impacts on the morphological and electronic properties of perovskite films between one-step and two-step method, and it brings insight into the strategy for extending the processing windows to achieve highly reliable PVSCs.

The low efficiency and fast degradation of devices from ink-jet printing process hinders the application of quantum dot light emitting diodes on next generation displays. Passivating the trap states caused by both anion and cation under-coordinated sites on the quantum dot surface with proper ligands for ink-jet printing processing reminds a problem. Here we show, by adapting the idea of dual ionic passivation of quantum dots, ink-jet printed quantum dot light emitting diodes with an external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours were reported for the first time. The liquid phase exchange of ligands fulfills the requirements of ink-jet printing processing for possible mass production. And the performance from ink-jet printed quantum dot light emitting diodes truly opens the gate of quantum dot light emitting diode application for industry., Designing efficient and scalable quantum dot LEDs meeting industrial requirements remains a challenge. Here, the authors, by leveraging the liquid phase exchange of d-MX2 ligands, present printed quantum dot LEDs with external quantum efficiency over 16% and half lifetime of more than 1,721,000 hours.

Due to a wide range of intriguing properties, such as efficient one-dimensional (1D) electron pathways and extraordinarily large surface areas, titanium dioxide (TiO2) nanotube arrays are considered as the promising electron transport material for high-performance perovskite solar cells (PVSCs). However, it is still a great challenge to directly synthesize the TiO2 nanotube arrays with well-controlled geometries (e.g., diameter and height, etc.) on the surface of fluorine-doped tin oxide (FTO). Here, vertically standing TiO2 nanotube arrays with desirable heights and diameters are directly synthesized on the FTO surface by employing the aqueous TiO2 sol-gel method on tubular photoresist templates. The tube height can be precisely tailored within a range of 350–900 nm for the effective loading of perovskite precursor solution. Importantly, it is demonstrated that TiO2 nanotube arrays with the optimized tube diameter and length can facilitate the infiltration of perovskite precursor solution, and thus ensuring the formation of a dense, smooth and large grain-sized perovskite film. Moreover, the contact between the perovskite and TiO2 nanotube arrays are enhanced simultaneously. Benefiting from the high-quality perovskite film, good interfacial contact at the perovskite/TiO2 tube interface, enhanced light trapping as well as rapid electron collection and transport induced by one-dimensional TiO2 nanotubes, the fabricated PVSCs exhibit an impressive power conversion efficiency (PCE) of up to 14.13%. Our work does not only demonstrate the promising potential of vertical TiO2 nanotube arrays for PVSCs, but also provides valuable insights into the design and utilization of TiO2 nanotubes for practical applications.

Mixed-halide wide-bandgap perovskites are key components for the development of high-efficiency tandem structured devices. However, mixed-halide perovskites usually suffer from phase-impurity and high defect density issues, where the causes are still unclear. By using in situ photoluminescence (PL) spectroscopy, it is found that in methylammonium (MA+ )-based mixed-halide perovskites, MAPb(I0.6 Br0.4 )3 , the halide composition of the spin-coated perovskite films is preferentially dominated by the bromide ions (Br- ). Additional thermal energy is required to initiate the insertion of iodide ions (I- ) to achieve the stoichiometric balance. Notably, by incorporating a small amount of formamidinium ions (FA+ ) in the precursor solution, it can effectively facilitate the I- coordination in the perovskite framework during the spin-coating and improve the composition homogeneity of the initial small particles. The aggregation of these homogenous small particles is found to be essential to achieve uniform and high-crystallinity perovskite film with high Br- content. As a result, high-quality MA0.9 FA0.1 Pb(I0.6 Br0.4 )3 perovskite film with a bandgap (Eg ) of 1.81 eV is achieved, along with an encouraging power-conversion-efficiency of 17.1% and open-circuit voltage (Voc ) of 1.21 V. This work also demonstrates the in situ PL can provide a direct observation of the dynamic of ion coordination during the perovskite crystallization.

Solution-processed organic light-emitting diodes (OLEDs) are currently attracting a lot of attention for their simple fabrication process. However, most laboratory-scale solution-processed devices are fabricated by spin-coating method which is not the optimum method for fabricating devices with a larger area as much of the material is wasted. Herein, a dip-coating method is introduced for its advantages for producing large-sized devices. The method is a more reliable and material saving fabrication process. In the present study, both the hole-transporting layer (HTL) and emitting layer (EML) were prepared by dip coating, and solution-processed green thermally activated delayed fluorescence (TADF) based OLEDs with high efficiencies were fabricated.

Developing facile strategies that enable high-performance perovskite solar cell (PSC) fabrication in ambient air is appealing yet challenging for low-cost and large-scale industrial deployment. However, attempts in this regard are still limited to methylammonium lead triiodide (CH3NH3PbI3), which lags significantly behind the rapid development of the state-of-the-art formamidinium (FA) based mixed perovskites. Here, a PbI2–(CsI)0.15–(FAI)x intermediate complex is proposed to unlock the processing limitation and efficiently facilitate the growth of high-quality mixed-cation Cs0.15FA0.85PbI3 perovskite films in ambient air with relative humidity (RH) as high as 70 ± 10%. It is found that the PbI2–(CsI)0.15–(FAI)x (x = 0.2 to 0.4) intermediate complex consisting of a mixture of composites is favorable for the conversion of PbI2 to high-quality Cs0.15FA0.85PbI3 perovskite. Eventually, it reduces the required FAI concentration deposited on the intermediate for the conversion of PbI2 to perovskite, which allows the strong hygroscopic FAI to be processed in ambient air. With the PbI2–(CsI)0.15–(FAI)0.3 intermediate complex, a low-temperature air-processed planar Cs0.15FA0.85PbI3 PSC achieves a champion power conversion efficiency (PCE) of 15.56% with superior thermal-stability and photo-durability, demonstrating its great potential for the large scale development of PSCs.

Mixed-organic-cation FA1−xMAxPbI3 perovskites are currently attracting intensive attention for their high photovoltaic performance. However, FA1−xMAxPbI3 usually has an undesired non-perovskite phase leading to a compromised efficiency, and a facile strategy to achieve pure-phase FA1−xMAxPbI3 has been rarely reported. Here, we demonstrate a facile approach to form δ-phase free FA1−xMAxPbI3 using a non-stoichiometric precursor solution. It is found that a small amount of excess methylammonium iodide (MAI) added to the precursor solution has a profound effect on perovskite crystallization during the liquid-to-solid phase transformation. Using an in situ photoluminescence spectroscopy measurement, it is found that the excess MAI can promote the formation of FA1−xMAxPbI3 and facilitate the cation-exchange between organic FA+ and MA+ during the film formation. Based on the optimized pure-phase FA1−xMAxPbI3, the perovskite solar cells exhibit an encouraging power conversion efficiency (PCE) of 17.40%. This study demonstrates a facile method to achieve high performance FA dominating mixed-organic-cation perovskite devices while providing insight into the ion-exchange process during perovskite crystallization.

A porphyrin-based donor material P1 is used to fabricate bulk-heterojunction solar cells harvesting room light. P1 consists of a porphyrin ring linked by two ethylrhodanine end caps via phenylene ethynylene bridges. Organic photovoltaic (OPV) cells using P1 as the donor exhibit significantly improved performances under indoor illumination compared to 1 sun conditions. For P1:PC71BM cells, an optimized-PCE of 19.2% was achieved under a 300 lux illumination of a 3000 K LED tube. Besides high PCEs, the porphyrin-based devices also exhibit enhanced OPV performances in thick film regions (∼200 nm) compared to a control BHJ cell using PCDTBT:PC71BM. The thick-film P1-based device shows an overall PCE of 18.2%. The origins of the thickness independent OPV performances were examined, and they can be attributed to the low electronic disorders of these materials when compared to their polymer counterparts.