The recently emerged integrated perovskite/bulk‐heterojunction (BHJ) organic solar cells (IPOSCs) without any recombination layers have generated wide attention. This type of device structure can ...take the advantages of tandem cells using both perovskite solar and near‐infrared (NIR) BHJ organic solar materials for wide‐range sunlight absorption and the simple fabrication of single junction cells, as the low bandgap BHJ layer can provide additional light harvesting in the NIR region and the high open‐circuit voltage can be maintained at the same time. This progress report highlights the recent developments in such IPOSCs and the possible challenges ahead. In addition, the recent development of perovskite solar cells and NIR organic solar cells is also covered to fully underline the importance and potential of IPOSCs.
Integrated perovskite/bulk‐heterojunction (BHJ) organic solar cells have shown great potential to further improve their performance by combining the advantages of perovskite solar cells and near‐infrared (NIR) BHJ organic solar cells. Combining with the maintained high VOC, higher efficiencies are expected by fully optimizing the perovskite layers and NIR BHJ layers through device engineering and materials innovations.
Because of the rapid rise of the efficiency, perovskite solar cells are currently considered as the most promising next‐generation photovoltaic technology. Much effort has been made to improve the ...efficiency and stability of perovskite solar cells. Here, it is demonstrated that the addition of a novel organic cation of 2‐(6‐bromo‐1,3‐dioxo‐1H‐benzodeisoquinolin‐2(3H)‐yl)ethan‐1‐ammonium iodide (2‐NAM), which has strong Lewis acid and base interaction (between CO and Pb) with perovskite, can effectively increase crystalline grain size and reduce charge carrier recombination of the double cation FA0.83MA0.17PbI2.51Br0.49 perovskite film, thus boosting the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 cell and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 cell. The champion cell shows efficiencies of 20.0% and 17.6% with active areas of 0.1 and 1.0 cm2, respectively. Moreover, the hysteresis behavior is suppressed and the stability is improved. The result provides a promising route to further elevate efficiency and stability of perovskite solar cells by the fine tuning of triple organic cations.
A new organic additive (2‐NAM) is introduced into the perovskite film. The introduction of this additive boosts the efficiency from 17.1 ± 0.8% to 18.6 ± 0.9% for the 0.1 cm2 area cells and from 15.5 ± 0.5% to 16.5 ± 0.6% for the 1.0 cm2 area cells. Moreover, the hydrophobic nature of this additive effectively reduces the influence from moisture, thus enhancing the solar cell stability.
III–V//Si multijunction solar cells offer a pathway to increase the power conversion efficiency beyond the fundamental Auger limit of silicon single‐junctions. In this work, we demonstrate how the ...efficiency of a two‐terminal wafer‐bonded III–V//Si triple‐junction solar cell is increased from 34.1 % to 35.9 % under an AM1.5g spectrum, by optimising the III–V top structure. This is the highest reported efficiency to date for silicon‐based multijunction solar cell technologies. This improvement was accomplished by two main factors. First, the integration of a GaInAsP absorber in the middle cell increased the open‐circuit voltage by 51 mV. Second, a better current matching of all subcells enhanced the short‐circuit current by 0.7 mA/cm2. Two different growth directions, upright and inverted, were investigated. The highest cell efficiency of 35.9 % (Voc = 3.248 V, jsc = 13.1 mA/cm2, FF = 84.3 %) was achieved with an upright grown structure. Processing of upright structures requires additional bonding steps, which results in a reduced homogeneity of cell performance across the wafer. A detailed comparison with the currently best triple‐junction solar cell reveals future improvement opportunities and limits, considering voltage and current, respectively.
A III‐V//Si triple‐junction solar cell with a record power conversion efficiency of 35.9 % under an AM1.5g spectrum is presented. The III–V top and the silicon bottom structures were monolithically connected by a direct wafer bond. The main improvements compared to the previous generation are the use of a GaInAsP absorber in the middle cell and better current match. This device achieves the highest conversion efficiency of all silicon‐based multijunction solar cells reported so far.
The status and problems of upscaling research on perovskite solar cells, which must be addressed for commercialization efforts to be successful, are investigated. An 804 cm2 perovskite solar module ...has been reported with 17.9% efficiency, which is significantly lower than the champion perovskite solar cell efficiency of 25.2% reported for a 0.09 cm2 aperture area. For the realization of upscaling high‐quality perovskite solar cells, the upscaling and development history of conventional silicon, copper indium gallium sulfur/selenide and CdTe solar cells, which are already commercialized with modules of sizes up to ≈25 000 cm2, are reviewed. GaAs, organic, dye‐sensitized solar cells and perovskite/silicon tandem solar cells are also reviewed. The similarities of the operating mechanisms between the various solar cells and the origin of different development pathway are investigated, and the ideal upscaling direction of perovskite solar cells is subsequently proposed. It is believed that lessons learned from the historical analysis of various solar cells provide a fundamental diagnosis of relative and absolute development status of perovskite solar cells. The unique perspective proposed here can pave the way toward the upscaling of perovskite solar cells.
Lessons learned from the historical analysis of diverse solar cells provide a fundamental diagnosis of the relative and absolute development status of perovskite solar cells. The upscaling of perovskite solar cells and commercialization of various solar cells are comparatively analyzed and feasible technologies that can be applied to the perovskite upscaling process, both now and in the future, are suggested.
Perovskite solar cells (PSCs) and organic solar cells (OSCs) face device efficiency losses and instability challenges with existing hole transport materials (HTMs). The development of new universal ...HTMs is in great demand to promote their practical applications. Herein, a versatile self‐assembled molecule (SAM) based HTM is designed for record‐high efficiency wide‐bandgap (WBG, Eg >1.75 eV) PSCs, all‐perovskite tandem solar cells (TSCs) and OSCs. The SAM exhibits high transmission and a lower‐lying energy level, enabling enhanced interfacial charge transfer and suppressed non‐radiative recombination losses. SAM based WBG PSCs deliver a maximum power conversion efficiency (PCE) of 18.63% with over 90% efficiency retention after 250 h continuous work. By stacking the optimal WBG PSC and a narrow‐bandgap PSC bottom cell, the 4‐terminal all‐perovskite TSC achieves a remarkable 26.24% PCE. More importantly, this SAM based HTM exhibits impressive generality in bulk heterojunction OSCs rivalling PEDOT:PSS, with an impressive PCE of 18.84% obtained for PM6:BTP‐eC9 based devices. When scaling up the PM6:BTP‐eC9 device to 0.5 cm2 in area (0.71 cm × 0.71 cm), the SAM based OSCs afford a highest PCE of 16.33%. This work provides a perspective for the design of universal SAM based charge transport materials targeting PSCs and OSCs for facile large‐area fabrication.
A versatile self‐assembled molecule (SAM) designed as a hole transport material layer enables impressive efficiencies of 18.63% and 26.24% for wide‐bandgap perovskite solar cells and 4‐terminal all‐perovskite tandem devices with long operational stability. Universality is successfully explored for state‐of‐the‐art organic solar cells, illustrated by 18.84% efficiency for a PM6:BTP‐eC9 system. This study is expected to inspire design of new SAMs for broad application prospects.
Semitransparent perovskite solar cells based on smooth perovskite films and ultrathin Cu (1 nm)/Au (7 nm) metal electrode demonstrate an efficiency of 16.5%. When illuminated through the ...semitransparent perovskite cell, a near‐infrared‐enhanced silicon heterojunction solar cell operates with 6.5% efficiency, leading to a total perovskite/silicon four‐terminal tandem efficiency of 23.0%.
Semitransparent perovskite solar cells (st‐PSCs) have received remarkable interest in recent years because of their great potential in applications for solar window, tandem solar cells, and flexible ...photovoltaics. However, all reported st‐PSCs require expensive transparent conducting oxides (TCOs) or metal‐based thin films made by vacuum deposition, which is not cost effective for large‐scale fabrication: the cost of TCOs is estimated to occupy ≈75% of the manufacturing cost of PSCs. To address this critical challenge, this study reports a low‐temperature and vacuum‐free strategy for the fabrication of highly efficient TCO‐free st‐PSCs. The TCO‐free st‐PSC on glass exhibits 13.9% power conversion efficiency (PCE), and the four‐terminal tandem cell made with the st‐PSC top cell and c‐Si bottom cell shows an overall PCE of 19.2%. Due to the low processing temperature, the fabrication of flexible st‐PSCs is demonstrated on polyethylene terephthalate and polyimide, which show excellent stability under repeated bending or even crumbing.
Fully solution‐processed transparent conducting oxide‐free semitransparent perovskite solar cells are reported to allow low‐cost fabrication of highly efficient tandem solar cells and flexible solar cells. Nitric acid annealed poly(3,4‐ethylenedioxythiophene): polystyrene sulfonate is incorporated in the fabrication process to realize high‐throughput printing of highly conductive transparent electrodes.
We show nanoscale phase stabilization of CsPbl₃ quantum dots (QDs) to low temperatures that can be used as the active component of efficient optoelectronic devices. CsPbl₃ is an all-inorganic analog ...to the hybrid organic cation halide perovskites, but the cubic phase of bulk CsPbl₃ (α-CsPbl₃)—the variant with desirable band gap—is only stable at high temperatures. We describe the formation of α-CsPbl₃ QD films that are phase-stable for months in ambient air. The films exhibit long-range electronic transport and were used to fabricate colloidal perovskite QD photovoltaic cells with an open-circuit voltage of 1.23 volts and efficiency of 10.77%. These devices also function as light-emitting diodes with low turn-on voltage and tunable emission.
Wide‐bandgap (WBG, ≈1.8 eV) perovskite is a crucial component to pair with narrow‐bandgap perovskite in low‐cost monolithic all‐perovskite tandem solar cells. However, the stability and efficiency of ...WBG perovskite solar cells (PSCs) are constrained by the light‐induced halide segregation and by the large photovoltage deficit. Here, a steric engineering to obtain high‐quality and photostable WBG perovskites (≈1.8 eV) suitable for all‐perovskite tandems is reported. By alloying dimethylammonium and chloride into the mixed‐cation mixed‐halide perovskites, wide bandgaps are obtained with much lower bromide contents while the lattice strain and trap densities are simultaneously minimized. The WBG PSCs exhibit considerably improved performance and photostability, retaining >90% of their initial efficiencies after 1000 h of operation at maximum power point. With the triple‐cation/triple‐halide WBG perovskites enabled by steric engineering, a stabilized power conversion efficiency of 26.0% in all‐perovskite tandem solar cells is further obtained. The strategy provides an avenue to fabricate efficient and stable WBG subcells for multijunction photovoltaic devices.
Efficient and photostable wide‐bandgap (WBG) perovskites (≈1.8 eV) with only 25 mol% bromide are enabled by steric engineering via alloying dimethylammonium and chloride. The WBG single‐junction cells, with a high efficiency of 17.7%, exhibit promising operational stability under 1‐sun illumination (T90 of 1045 h). This strategy enables all‐perovskite tandem with an impressive stabilized efficiency of 26.0%.
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