Chen Weijie

All-small-molecule organic solar cells (ASM-OSCs) have achieved exciting research progress in recent years. A brief summary from the perspective of materials, morphology, and device optimization techniques have been performed, which will provide valuable guidelines for further enhancement in ASM-OSCs area.

Abstract

Active layer material plays a critical role in promoting the performance of an organic solar cell (OSC). Small-molecule (SM) materials have the merits of well-defined chemical structures, few batch-to-batch variations, facile synthesis and purification procedures, and easily tuned properties. SM-donor and non-fullerene acceptor (NFA) innovations have recently produced all-small-molecule (ASM) devices with power conversion efficiencies that exceed 17% and approach those of their polymer-based counterparts, thereby demonstrating their great future commercialization potential. In this review, recent progress in both SM donors and NFAs to illustrate structure–property relationships and various morphology-regulation strategies are summarized. Finally, ASM-OSC challenges and outlook are discussed.

A novel facial mask (FM) strategy is developed to incubate high-quality perovskite films via simultaneously regulating perovskite crystal growth and modifying the surface properties. The FM-based perovskite films exhibit smooth morphology, increased (100) crystal orientation in the out-of-plane direction, and well-adjusted energy-levels, thereby delivering a promising efficiency of 21.4% with improved humidity/thermal stability for MAPbI₃-based PSCs.

Abstract

High-performance perovskite film with superior internal and surface qualities is critical for perovskite solar cells (PSCs) but hardly achievable due to the rapid crystallization rate of perovskite itself. Herein, a novel technique by in situ manipulating perovskite crystal growth and modifying the surface properties is developed using organic passivating agent-assisted polydimethylsiloxane membrane as a facial mask (FM) of perovskites. By placing the perovskite-precursor films with their faces toward the designed FM during thermal annealing, a favorable microenvironment is constructed for incubating high-quality perovskite films with smooth surface, enhanced vertical orientation of (100) plane, and well-adjusted interfacial energy levels. With this versatile FM incubation technique, efficient PSCs for both methylammonium (MA)-based and formamidinium (FA)-MA-Cs mixed perovskite systems are facilely fabricated, delivering excellent humidity/thermal stabilities and promising efficiencies up to 21.4% with an improved open-circuit voltage of 1.15 V in MA-based devices. This study not only provides a facile and efficient approach to rationally manage the perovskite growth process, but also reveals the fundamental characteristics of high-quality perovskite films comprehensively for the construction of efficient and stable PSCs.

Low-temperature solution-processed Co-La-based hole transporting layers were developed for organic solar cells with high power conversion efficiency (18.82 %), superior reproductivity and long-term stability.

Abstract

Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is a widely used hole transporting layer (HTL) in organic solar cells (OSCs), but its acidity severely reduces the stability of devices. Until now, very few HTLs were developed to replace PEDOT:PSS toward stable and high-performance OSCs. Herein, a new cobalt-lanthanum (Co-La) inorganic system was reported as HTL to show a high conversion efficiency (PCE) of 18.82 %, which is among the top PCEs in binary OSCs. Since electron-rich outer shell of La atom can interact with Co atom to form charge transfer complex, the work function and conductivity of the Co-La system could be simultaneously enhanced compared to Co or La-based HTLs. This Co-La system could also be applied into other OSCs to show high performance. All these results demonstrate that binary Co-La systems as HTL can efficiently tackle the issue in hole transporting and show powerful application in OSCs to replace PEDOT:PSS.

A scalable, low temperature, and in-air environment process by blade-coating technique is presented to fabricate efficient, low energy demanding, and highly transparent perovskite solar cells. A systematic study of the fabrication process using the indium tin oxide (ITO)/SnO₂/FaPbBr₃/PTAA/ITO device stack is developed. Blade-coated FaPbBr₃ device reached a maximum power conversion efficiency (PCE) equal to 5.8%, an average visible transmittance (AVT) of 52.3%, and a bifaciality factor of 86.5%.

Perovskite photovoltaics (PVs) is an emerging PV technology that attracts interest thanks to an unprecedented combination of properties, including the ease of the bandgap tunability. The feasibility to deploy wide bandgap absorbers (>2.2 eV) leading to high average visible transmittance (AVT) is particularly intriguing for building-integrated PVs, in particular for smart windows, façades, and agrivoltaics. However, research on this topic is still at the initial stage, especially concerning the development of scalable deposition techniques. Uniform coverage and morphology control of bromide perovskite film are the main issues to tackle. Herein, a systematic study on the development of FAPbBr₃-based semi-transparent perovskite solar cell (ST-PSC) is presented by replacing spin-coating as the main deposition technique used for the device fabrication. To tackle this topic, the blade coating technique is employed to obtain a manufacturing flow performed at low temperature in the air environment. The results for the blade-coated device show a power conversion efficiency of 5.8%, AVT of 52.3%, and bifacial factor of 86.5%. Moreover, scalable and uniform FAPbBr₃ deposition on 300 cm² substrates is presented for the first time. The combination of low temperature, scale-up capability, and air processing along with promising PV performances represent a feasible platform for the future exploitation of PSC in building integrated photovoltaic.

A low-temperature processed PC61BM:ZnO hybrid thin film is developed using a PC61BM-doped diethylzinc precursor. The structural, chemical, optical, and electrical characterizations of PC61BM-doped ZnO establish it as an efficient cathode buffer layer (CBL) for interface engineering in organic solar cells. The optimized energy-level alignment at the CBL interface is realized because of surface-rich self-assembled graded fullerene isomers.

In organic solar cells (OSCs), improving the properties at the interface of the bulk heterojunction (BHJ) photoactive layer and the buffer layer is desired, but achieving a high-quality interface between these two layers is inevitably challenging. Herein, a novel (PC61BM)-doped zinc oxide, that is, a (PC61BM-ZnO)_DEZ hybrid thin film, is proposed for application as a cathode buffer layer (CBL) for OSCs based on both fullerene-based acceptors and nonfullerene acceptors. These thin films require low annealing temperatures and can be deposited via a one-step solution-processable method using a hybrid precursor composed of PC61BM and diethylzinc solution (DEZ). The study reveals that the performance of devices with (PC61BM-ZnO)_DEZ hybrid thin films as a CBL exceeds that of devices with thin films of conventional ZnO as a CBL. Impedance analysis of the fabricated OSCs suggests improved charge collection efficiency in the devices with (PC61BM-ZnO)_DEZ thin film. Optical, electrical, morphological, and compositional characterizations of thin films used as CBLs confirm the presence of a PC61BM-rich phase with traces of d-C61 (fullerene dimer) at the surface of the hybrid (PC61BM-ZnO)_DEZ thin film. These phases help in tuning the interfacial properties by ensuring better coupling between the BHJ photoactive layer and the CBL.

A functionalized interfacial passivation layer, a kind of self-assembled monolayer, is developed to modify TiO₂/perovskite interfaces. With the synergistic contribution of defect passivation and charge transfer improvement, as high as 24.8% efficiency with negligible hysteresis is achieved for TiO₂-based planer perovskite solar cells (PSCs), meanwhile, the perovskite films exhibit excellent moisture stability and the PSC devices have excellent operational stability.

Abstract

Self-assembled monolayers (SAMs) with unique ordered structures and varied anchoring groups have emerged as an excellent interfacial strategy for perovskite solar cells (PSCs). Herein, 3-carboxypropyl-triphenyl phosphonium bromide with the participation of the fullerene derivative [6,6]-phenyl-C₆₁-butyric acid (PCBA) as functionalized C-PCBA SAM, is introduced to stably modify the TiO₂/perovskite interface. In the meantime, with strong fullerene cage–iodide interaction, ordered C-PCBA SAM can passivate interfacial defects and improve the electron transportation. A high efficiency of 24.8% and stabilized power output of 23.9%, are achieved with negligible hysteresis, which is among the best performances for TiO₂ planar PSCs. This modified cell also exhibits significantly improved stabilities under different testing conditions; non-encapsulated devices can maintain 95% of initial efficiency after 1000 h thermal stability testing at 85 °C and 85% after 700 h continuous illumination (≈100 mW cm⁻²) and maximum-power-point tracking. This work provides valuable inspiration for developing highly efficient and stable PSCs by using a convenient SAM reconfiguration strategy.

Incorporation of a strong polar substituent on a non-fused acceptor core can help to reduce donor-acceptor (D : A) miscibility, leading to optimized D : A morphology and domain purity in fully non-fused organic photovoltaic (OPV) cells. Using this approach, high-efficient and stable OPV cells are achieved.

Abstract

To modulate the miscibility between donor and acceptor materials both possessing fully non-fused ring structures, a series of electron acceptors (A4T-16, A4T-31 and A4T-32) with different polar functional substituents were synthesized and investigated. The three acceptors show good planarity, high conformational stability, complementary absorption and energy levels with the non-fused polymer donor (PTVT-BT). Among them, A4T-32 possesses the strongest polar functional group and shows the highest surface energy, which facilitates morphological modulation in the bulk heterojunction (BHJ) blend. Benefiting from the proper morphology control method, an impressive power conversion efficiency (PCE) of approaching 16.0 % and a superior fill factor over 0.795 are achieved in the PTVT-BT : A4T-32-based organic photovoltaic cells with superior photoactive materials price advantage, which represent the highest value for the cells based on the non-fused blend films. Notably, this cell maintains ≈84 % of its initial PCE after nearly 2000 h under the continuous simulated 1-sun-illumination. In addition, the flexible PTVT-BT : A4T-32-based cells were fabricated and delivered a decent PCE of 14.6 %. This work provides an effective molecular design strategy for the non-fused non-fullerene acceptors (NFAs) from the aspect of bulk morphology control in fully non-fused BHJ layers, which is crucial for their practical applications.

The surface regulation of 3D perovskite through dipolar 4-trifluoromethylbenzamidine hydrochloride (TFPhFACl) molecule results in an impressive efficiency of 24.0%. The formation of dipolar layer not only accelerates the hole transporting from 3D perovskite to spiro-MeOTAD, but also suppresses the nonradiative recombination through the coordination of TFPhFA⁺ cations with Pb–I octahedron.

Abstract

Mixed 2D/3D perovskite solar cells (PSCs) show promising performances in efficiency and long-term stability. The functional groups terminated on a large organic molecule used to construct 2D capping layer play a key role in the chemical interaction mechanism and thus influence the device performance. In this study, 4-(trifluoromethyl) benzamidine hydrochloride (TFPhFACl) is adopted to construct 2D capping layer atop 3D perovskite. It is found that there are two mechanisms synergistically contributing to the increase of efficiency: 1) The TFPhFA⁺ cations form a dipole layer promoting the interfacial charge transport. 2) The suppressed nonradiative recombination of perovskite through the coordination of TFPhFA⁺ cations with Pb–I octahedron, as well as the recrystallization of 3D perovskite induced by Cl^- ions. As a result, the PSC delivers an efficiency of 24.0% with improved open-circuit voltage (V _OC) of 1.16 V, short-circuit current density (J _SC) of 25.42 mA cm^-2, and fill factor of 81.26%. The device shows no decrease in efficiency after 1500 h stored in the air indicating the good stability. The utilization of TFPhFACl not only provides a facile way to optimize the interfacial problems, but also gives a new perspective for rational design of large spacer molecule for constructing efficient 2D/3D PSCs.

A charge-carrier-dynamic management strategy for inorganic perovskite/organic tandem solar cells (TSCs) is conducted to narrow the hole/electron density offset in the interconnecting layer, which contributes to a balanced charge carrier recombination thus reducing the energy loss of the TSCs. A promising 23.17% power conversion efficiency, an ultrahigh open-circuit voltage of 2.15 V, and robust operational stability are obtained.

Abstract

The charge carriers of single-junction solar cells can be fluently extracted and then collected by electrodes, leading to weak charge carrier accumulation and low energy loss (E _loss). However, in tandem solar cells (TSCs), it is a considerable challenge to obtain a balance between the densities of the holes and electrons extracted from the two respective subcells to facilitate an efficient recombination in the interconnecting layer (ICL). Herein, a charge-carrier-dynamic management strategy for inorganic perovskite/organic TSCs is proposed, centered on the simultaneous regulation of the defect states of CsPbI_1.9Br_1.1 perovskite in the front subcell and hole transport ability from the perovskite to ICL. The target hole density on the perovskite surface and the hole loss before reaching the ICL are significantly improved. As a result, the hole/electron density offset in the ICL can be effectively narrowed, leading to a balanced charge carrier recombination, which reduces the E _loss in TSCs. The resulting inorganic perovskite/organic 0.062-cm² TSC exhibits a remarkable power conversion efficiency (PCE) of 23.17% with an ultrahigh open-circuit voltage (V _oc) of 2.15 V, and the PCE of the 1.004-cm² device (21.69%) exhibited a weak size-dependence. This charge-carrier-dynamic management strategy can also effectively enhance the operational and ultraviolet-light stabilities of the TSCs.

Perovskite solar cells (PSCs) via the two-step sequential deposition show advantages of easy fabrication and decent performance repeatability. Whereas, it is still challenging to implement this technique in the inverted PSCs. Here, an improved sequential two-step method for inverted PSCs is demonstrated by a binary modulation system and a champion efficiency of 23.4% is realized with remarkable device stability.

Abstract

Inverted-structure metal halide perovskite solar cells (PSCs) have attractive advantages like low-temperature processability and outstanding device stability. The two-step sequential deposition method shows the benefits of easy fabrication and decent performance repeatability. Nevertheless, it is still challenging to achieve high-performance inverted PSCs with similar or equal power conversion efficiencies (PCEs) compared to the regular-structure counterparts via this deposition method. Here, an improved two-step sequential deposition technique is demonstrated via treating the bottom organic hole-selective layer with the binary modulation system composed of a polyelectrolyte and an ammonium salt. Such improved sequential deposition method leads to the spontaneous refinement of up and buried interfaces for the perovskite films, contributing to high film quality with significantly reduced defect density and better charge transportation. As a result, the optimized PSCs show a large enhancement in the open-circuit voltage by 100 mV and a dramatic lift in the PCE from 18.1% to 23.4%, delivering the current state-of-the-art performances for inverted PSCs. Moreover, good operational and thermal stability is achieved upon the improved inverted PSCs. This innovative strategy helps gain a deeper insight into the perovskite crystal growth and defect modulation in the inverted PSCs based on the two-step sequential deposition method.

Herein, two kinds of amino acids (l-arginine and l-glutamate) with different isoelectric points (l-arginine is 10.76 and l-glutamate is 3.22) passivate the defects with different functional groups. Device efficiency is boosted from 20.23% to 22.96% and 22.66%, and humidity stability and thermal stability are also improved at different levels.

As a multigroup cross-linking agent, amino acid derivatives contain different kinds of characteristic functional groups with different characteristics. Aiming at one of the most difficult problems, ionic defects, amino acid derivatives can passivate these defects through their multifunctional groups. Ionic defects (such as organic cations and halogen anions) mostly exist on surface and/or grain boundaries of perovskite films, and amino acid derivatives promote the formation of high-quality perovskite films by coordinating well with these defects. Herein, the effects of two kinds of amino acids (l-arginine and l-glutamic acid) with contrastive isoelectric points (pIs) on perovskite film formation, defect passivation mechanism, device efficiency, flexible substrate, and thermal/moisture stability are studied. Efficiency of inverted perovskite solar cells is improved from ≈20% to nearly 23% with additives on rigid substrates. High pI l-arginine improves the open-circuit voltage significantly, while low pI l-glutamic acid excels in fill factor and short-circuit current. More importantly, low pI l-glutamic acid shows superior thermal and moisture stability, indicating inherent stronger bonding between l-glutamic acid and perovskite.

High performance tandem all-polymer solar cells are fabricated by employing two complementary absorbing polymerized small molecule acceptors (PSMAs), a wide-band gap PSMA PIDT in front cell with PM7 as polymer donor and a narrow-bandgap PSMA PY-IT in rear cell with PM6 as polymer donor. The optimized device demonstrates a high power conversion efficiency of 17.87% with V _oc reaching 2.00 V.

Abstract

All-polymer solar cells (all-PSCs) possess distinguished advantages of excellent morphology stability, thermal stability, and mechanical flexibility. Tandem solar cells, by stacking two sub-cells, can absorb more photons in a wider wavelength range and can reduce thermal losses. However, limitation of polymer acceptors with suitable bandgaps hinders the development of tandem all-PSCs. Herein, highly efficient tandem all-PSCs are fabricated by employing two polymerized small molecular acceptors (PSMAs) of wide bandgap PIDT (1.66 eV) in the front cell and narrow bandgap PY-IT (1.4 eV) in the rear cell. The two sub-cells with the polymer donors of PM7 in front cell and PM6 in rear cell show high open circuit voltage (V _oc) of 1.10 V for the front cell and 0.94 V for the rear cell. By rational device optimizations, the best power conversion efficiency of 17.87% is achieved for the tandem all-PSCs with high V _oc of 2.00 V. 17.87% is one of the highest efficiency for the all-PSCs, and 2.00 V is one of the highest V _oc for all the tandem organic solar cells. Moreover, the tandem all-PSCs show excellent thermal and light-soaking stability compared with their small-molecule counterparts. The results provide insight to the potential of bandgap tuning in PSMAs, and indicate that the tandem architecture is an effective strategy to boost performance of the all-PSCs.

Analyzing the current matching situation in perovskite/silicon tandem solar cells by integrating measured external quantum efficiencies can lead to misinterpretations. Spectrometric characterization is presented as an alternative approach. Current–voltage curves are recorded under different spectral conditions, which allow for accurate determination of the current matching point and give insight in the influence of the single subcells on the tandem performance.

In monolithic perovskite/silicon tandem solar cells, it is important to know which subcells are limiting the overall current to adapt the perovskite absorber thickness and bandgap accordingly. The current matching situation is usually analyzed by integrating measured external quantum efficiencies. However, this method can lead to significant errors and misinterpretations if metastable perovskite solar cells are involved. Herein, spectrometric characterization is presented as an alternative approach avoiding these errors. Current–voltage curves are recorded under different spectral conditions. Spectral irradiance settings are varied in a systematic way from redshifted spectra (the perovskite top solar cell limits the current) to blueshifted spectra (the silicon bottom solar cell limits the current) around the air mass 1.5 global (AM1.5G) spectrum. This method not only allows for accurate determination of the current matching point, but also gives quantitative insight in the behavior of the single subcells and their influence on the tandem performance. As different current mismatching also influences other global cell parameters, an example is presented where the current loss due to the current mismatch is partly compensated by a strong fill factor increase when the silicon solar cell limits the current, resulting in a high-power output also at the AM1.5G condition.

A dopant-free polymeric hole transport material (HTM) is designed and synthesized using a thienothiophene group as a π-bridge to connect donors and acceptors, and remarkable power conversion efficiency over 23% and long-term stability are achieved in perovskite solar cells (PSCs), which offers a practical method to enhance photovoltaic performance of dopant-free HTM-based PSCs.

Abstract

Hole transport materials (HTMs) play essential roles in achieving high photovoltaic performance and long-term stability in the n–i–p structure of perovskite solar cell (PSC) devices. Recently, dopant-free polymeric materials as HTMs in PSCs have attracted considerable attention owing to high carrier mobility and excellent hydrophobicity. However, achieving similar efficiencies to those of doped small molecule HTMs such as Spiro-OMeTAD is a big challenge. Herein, a thienothiophene π-bridge is selected as a stabilizer and energy level regulator incorporated into a donor–acceptor-type HTM to synthesize a new polymer, Nap-SiBTA. The incorporation of the thienothiophene group improves the thermal stability and favors the high planarity and face-on orientation, promoting high charge carrier mobility and tunable optical band gap. Finally, the dopant-free polymer Nap-SiBTA-based PSC achieves an excellent power conversion efficiency (PCE) of 23.07% with a high fill factor of 80.85%. To the best of the authors’ knowledge, this is one of the best efficiencies in dopant-free HTM PSCs. Moreover, the unencapsulated device retains 93% of its initial PCE after 1000 h owing to the excellent hydrophobicity of Nap-SiBTA. This work provides a general and practical method to design dopant-free HTMs for the high efficiency and long-term stability of PSCs.

In situ X-ray scattering is applied to investigate the structure evolution pathway of the 2D phase atop 3D perovskite. By manipulating the phase transition pathway, the gradient distribution from 3D to n = 2 and n = 1 phase is realized in final films which helps charge separation and extraction, finally concurrently boosted the device stability and efficiency.

Abstract

Manipulating the formation process of the 2D/3D perovskite heterostructure, including its nucleation/growth dynamics and phase transition pathway, plays a critical role in controlling the charge transport between 2D and 3D crystals, and consequently, the scalable fabrication of efficient and stable perovskite solar cells. Herein, the structural evolution and phase transition pathways of the ligand-dependent 2D perovskite atop the 3D surface are revealed using time-resolved X-ray scattering. The results show that the ligand size and shape have a critical influence on the final 2D structure. In particular, ligands with smaller sizes and more reactive sites tend to form the n = 1 phase. Increasing the ligand size and decreasing the reactive sites promote the transformation from 3D to n = 3 and n < 3 phases. These findings are useful for the rational design of the phase distribution in 2D perovskites to balance the charge transport and stability of the perovskite films. Finally, solar cells based on ambient-printed CsPbI₃ with n-butylammonium iodide treatment achieve an improved efficiency of 20.33%, which is the highest reported value for printed inorganic perovskite solar cells.

Two non-fused ring electron acceptors (NFREAs) have been developed. The halogen substituents on the aromatic side chains, as the new structure design tools, not only facilitate the construction of 3D stacks in solid, but also optimize the optoelectronic properties of the NFREAs, leading to organic solar cells with 16.2 % efficiency and excellent operational stability.

Abstract

Searching the cost-effective organic semiconductors is strongly needed in order to facilitate the practice of organic solar cells (OSCs), yet to be fulfilled. Herein, we have succeeded in developing two non-fused ring electron acceptors (NFREAs), leading to the highest efficiency of 16.2 % for the NFREA derived OSCs. These OSCs exhibit the superior operational stabilities under one sun equivalent illumination without ultraviolet (UV) filtration. It is revealed that the modulation of halogen substituents on aromatic side chains, as the new structural tool to tune the intermolecular interaction and optoelectronic properties of acceptors, not only promotes the interlocked tic-tac-toe frame of three-dimensional stacks in solid, but also improves charge dynamics of acceptors to enable high-performance and stable OSCs.

Methylammonium iodide/isopropyl alcohol as a secondary anti-solvent strategy is proposed and further reduces surface defects by nearly two orders based on conventional surface post-treatment. This treatment allows the use of another passivation material to simultaneously manipulate the surface defects and can optimize the crystallization of films. The optimized performance of the 2D Dion–Jacobson perovskite device of 19.55% is achieved.

Abstract

Surface defects-mediated nonradiative recombination plays a critical role in the performance and stability of perovskite solar cells (PSCs) and surface post-treatment is widely used for efficient PSCs. However, the commonly used surface passivation strategies are one-off and the passivation defect ability is limited, which can only solve part of the defects in the topmost surface area. Here, a secondary anti-solvent strategy is proposed to further reduce surface defects based on conventional surface passivation for the first time. Based on this, the crystallization quality of 2D Dion–Jacobson perovskite is enhanced and the surface defects density is further reduced by nearly two orders. In addition, a gradient structure of perovskite with n = 2 phases located at the top of the film and 3D-like phases located at the bottom of the film can also be obtained. The modulated perovskite film boosts the efficiency of 2D perovskites (n = 5) up to 19.55%. This strategy is also very useful in other anti-solvent processed perovskite dipping systems, which paves a promising avenue for minimizing surface defects toward highly efficient perovskite devices.

Perovskite solar cells (PSCs) mounted on a high-altitude balloon are launched into near-space. During the 19-h flight, the PSCs are exposed directly to near space. Then, the diurnal performance evolution of PSCs is obtained for the first time, and strikingly, they deliver a high energy density comparable to that of silicon solar cells.

Abstract

Perovskite solar cells (PSCs), have exhibited potential value for revolutionizing photovoltaic technology for space applications, and they have passed a series of tests in a simulated space environment. Nevertheless, the simulated space environment on land is definitely distinguished from the real-space conditions, and the results cannot completely represent the real operating state of PSCs in space. Herein, PSCs mounted on a high-altitude balloon are launched into near-space and the current–voltage characteristics are measured in situ throughout the 19-h flight, during which the PSCs are exposed directly to near-space and experience wide temperature variation, vacuum, and strong irradiation. Thus, the diurnal performance evolution of PSCs is obtained for the first time and a possible variation mechanism is identified. The PSCs present expected stability and a champion power density of ≈12 mW cm⁻² at noon, which is demonstrated as the highest result achieved in near-space for PSCs. Additionally, despite a complex degradation process, the PSCs still deliver a high energy density comparable to that of silicon solar cells. Finally, the challenges facing the space application of PSCs are discussed. This work highlights the feasibility of PSCs in near space and provides direction for further exploration.