Low-temperature processed high-performance flexible perovskite solar cells via rationally optimized solvent washing treatments

ABX3 Perovskites for Tandem Solar Cells

Carrier Dynamics Engineering for High-Performance Electron-Transport-Layer-free Perovskite Photovoltaics

Realizing the commercialization of high-performance and robust perovskite solar cells urgently requires the development of economically scalable processing techniques. Here we report a high-throughput ultrasonic spray-coating (USC) process capable of fabricating perovskite film-based solar cells on glass substrates with a power conversion efficiency (PCE) as high as 13%. Perovskite films with high uniformity, crystallinity, and surface coverage are obtained in a single step. Moreover, we report USC processing on TiO2/ITO-coated polyethylene terephthalate (PET) substrates to realize flexible perovskite solar cells with a PCE as high as 8.1% that are robust under mechanical stress. In this case, a photonic curing technique was used to achieve a highly conductive TiO2 layer on flexible PET substrates for the first time. The high device performance and reliability obtained by this combination of USC processing with optical curing appear very promising for roll-to-roll manufacturing of high-efficiency, flexibl...

High-performance methylammonium-free ideal-band-gap perovskite solar cells

Here, we show that flexible perovskite solar cells (PSCs) with high operational stability and power conversion efficiency (PCE) approaching 20% were achieved by elastic grain boundary (GB) encapsul...

Decoupling the effects of defects on efficiency and stability through phosphonates in stable halide perovskite solar cells

Lead-free tin perovskite solar cells

Emerging hybrid organic–inorganic perovskites with superior optoelectronic property demonstrate promising prospect for photovoltaic (PV) applications, in particular for low-lighting indoor applications e.g. within internet of things (IoT) networks or low-energy wireless communication devices. In order to prepare devices with high power output under low-illumination conditions, scalable fabrication techniques are preferred for large-area perovskite solar cells. In additions, one of the key parameters to achieve high-efficiency large-area perovskite solar cells is to minimize the ohmic loss to further boost the solar cell efficiency. Herein, a one-step blade-coating method assisted by hexafluorobenzene (HFB) was developed to deposit dense, large-area smooth and high-quality perovskite films with low ohmic loss. The as-fabricated devices demonstrated power conversion efficiency (PCE) of 20.7% (area of 0.2 cm2) and 16.5% (1 cm2), respectively, under standard (AM 1.5G) illumination conditions. Besides, the large-area (1 cm2) devices demonstrated a remarkable PCE of ∼ 33.8% and ∼ 30.0% under 1000 lx and 100 lx illumination provided by white light-emitting diode (LED) lamp, respectively. We exhibited a series-connected stack of large-area (totally active area ∼ 4 cm2) perovskite photovoltaic device powering up a LED under common indoor environment as an indoor self-power indicator lamp. The analysis using a single diode model suggests that the high performance of the large-area devices under low-lighting indoor conditions is highly associated with the largely reduced ohmic losses, which particularly indicate that the perovskite films by a facile and scalable blade-coating method. The presented scalable approach paves the way to designing high-performance perovskite solar cells for a variety of emerging indoor PV applications.

Low temperature, stable and facile solution processes are the typical characters in mass production of next generation solar cells, especially for flexible consumable electronics. In this work, we employed a low cost, chemical stable, solution processing polymer, thermal treatment free poly(2-ethyl-2-oxazoline) (PEOz) nanodots, as an efficient interfacial layer on top of [6,6]-phenyl-C61-butyricacid methyl (PCBM) to fabricate inverted planar heterojunction (PHJ) perovskite solar cells. The performance of perovskite solar cells increased from 9.01% to 14.52% after inserting a thin layer of PEOz between PCBM and Ag. It was demonstrated that PEOz can effectively reduce the work function of silver electrode to form an ohmic contact between PCBM and silver, which dramatically enhance the electron extraction capability from PCBM to silver electrode. This study pays a way for the large scale fabrication of high efficiency perovskite thin film solar cells via low cost solution processing at low temperatures.

Stable self-assembled monolayers (SAMs), such as (2-(9H-carbazol-9-yl)) ethylphosphonic acid (2PACz), are crucial for reducing interfacial energy loss in high-performance perovskite solar cells (PSCs). However, the inherent aggregation tendency of SAMs at the buried interface hinders the device’s performance. Here, we propose a surfactant-assisted strategy to inhibit the aggregation of 2PACz by functionalizing cetyltrimethylammonium bromide (CTAB). Capitalizing on its distinctive electrostatic potential distribution, CTAB engages in non-bonding interactions with 2PACz. Theoretical and experimental characterizations prove that this promotes the uniform dispersion and anchoring of 2PACz on the substrate, leading to the SAM formation with high surface potential and excellent coverage. Moreover, the perovskite films with CTAB-modified SAM exhibit enhanced crystallinity with reduced trap state density and improved hole extraction efficiency. Consequently, the PSCs with a p-i-n architecture achieve a power conversion efficiency (PCE) of 26.20% (0.072 cm²). Scaled-up modules attain a PCE of 22.34% (22.96 cm²), confirming the scalability. Additionally, anti-aggregation-SAMs-integrated devices demonstrate stability, maintaining over 80% and 90% of their initial PCEs after tracking at maximum power point for 800 h and ageing at 65 °C for 1000 h, respectively.

Electrode Design to Overcome Substrate Transparency Limitations for Highly Efficient 1 cm2 Mesoscopic Perovskite Solar Cells

A new set of simply structured triphenylamine-based small molecules are synthesized and evaluated as dopant-free hole transporting materials (HTMs) for high-performance perovskite solar cells (PSCs) and bulk heterojunction inverted organic solar cells (BHJ IOSCs). Surprisingly, the new amphiphilic-type HTM-1 (with internal hydrophilic groups and peripheral hydrophobic alkyl tails) showed better compatibility and performance than the actual target molecule, that is, HTM-2 in PSCs and BHJ IOSCs. Importantly, the HTM-1-based dopant-free PSCs and BHJ IOSCs exhibited high power conversion efficiencies (PCEs) of 11.45 % and 8.34 %, respectively. These performances are superior and comparable to those of standard HTMs Spiro-OMeTAD (2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene) and PEDOT:PSS (poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate) in PSCs and BHJ IOSCs, respectively. The enhanced device performance of the HTM-1-based PSCs is ascribed to its strong affinity towards the perovskite, properly aligned energy levels with respect to the perovskite valence band, and excellent hole transporting behavior. In addition, the well-organized energy levels of the HTMs showed excellent compatibility in BHJ IOSCs. The new amphiphilic-type HTM-based photovoltaic devices also showed long-term air stability over 700 h. These promising results offer new and unexpected prospects for engineering the interface between the photoactive material and HTMs in PSCs and BHJ IOSCs.

Rubidium based new lead free high performance perovskite solar cells with SnS2 as an electron transport layer

A tailored TiO2 electron selective layer for high-performance flexible perovskite solar cells via low temperature UV process

To date, antisolvent treatment has become one of the most important means to fabricate high efficiency perovskite solar cells (PSCs); however, the few reported antisolvents have not been analyzed on a uniform platform, and there is hitherto no clear reasoning in the choice of antisolvents toward high performance PSCs. Here, we study the role of the antisolvents in the nucleation kinetics of perovskite solutions and their residual influence on perovskite crystal growth, film formation, and device performance. Through X-ray diffraction analysis on the complicated double mixed perovskite, we qualitatively evaluate the impact of thermal annealing and antisolvent treatment (A.S.T.) on the phase composition and microstructure of the films. By using miscible antisolvents with high boiling point instead of immiscible low boiling point solvents, we obtain homogeneous and almost pinhole-free perovskite films. When using trilluorotoluene (TFT) to replace toluene and chlorobenzene as a novel antisolvent, we achieve a power conversion efficiency (PCE) of 20.3% under optimized device fabrication conditions with a composite perovskite as active layer. The conclusions from this study should assist in establishing reproducible fabrication processes and finding better antisolvent candidates for perovskite solar cells.