Highly efficient and reproducible cesium (Cs) doped triple cation (Cs, methylammonium (MA) and formamidinium (FA)) lead trihalide perovskite planar heterojunction (PHJ) solar cells are fabricated via low-temperature process with a simple architecture of ITO/SnO 2 /Perovskite/Spiro-OMeTAD/ Ag, of which the power conversion efficiency (PCE) up to 20.51% with negligible hysteresis and a steady output PCE of 20.22% can be achieved. Cs-intercalation is useful for forming high-quality Cs-doped triple cation perovskite films with larger gains and band gap as compared with perovskite films without Cs doping, leading to impressively enhanced photoluminescence lifetime and open circuit voltage (V oc ). Meanwhile, incorporating Cs þ into perovskite structure can result in lower charge-extraction time and prolonged charge-recombination lifetime, which are advantageous to improve the device performance. More importantly, Cs-doped triple cation PHJ perovskite solar cells (PSCs) exhibit better stability. They could maintain about 80% original PCE even exposed to air environments (humidity %40%) for over 500 hr without any encapsulation, while similar ones without Csdoping only maintain about 60% original PCE. The research work demonstrates that triple or multiple cation mixture is an effective strategy for structuring highly-efficient and stable PHJ-PSCs via low-temperature process, which may accelerate the commercialization of PSCs fabricated via large-scale printing techniques.
Flexible perovskite network photodetectors based on the bulk heterojunction (BHJ) of CH3NH3PbI3 and an organic semiconductor dioctylbenzothieno [2,3-b] benzothiophene (C8BTBT) have been fabricated via a simple, one-step solution process. The responsivity, detectivity, and response time as the critical parameters of CH3NH3PbI3/C8BTBT BHJ network photodetectors reach 8.1 AW−1, 2.17 × 1012 Jones, and 7.1 ms, respectively. Meanwhile, they can maintain over 70% of original performance even when exposed to ambient conditions (humidity ∼ 45%) for 50 days without encapsulation. Furthermore, the CH3NH3PbI3/C8BTBT BHJ network photodetectors fabricated on a polyethylene terephthalate (PET) substrate exhibit superior flexibility at different bending radii and large numbers of bending cycles. The photocurrent just shows a decrease of less than 5% as the devices are bent for 10 000 cycles at a small radius of 7.5 mm. The present research indicates that BHJ networks composed of perovskites and organic semiconductors open up the exciting opportunity for fabricating high-performance, low-cost, flexible electronic and optoelectronic devices.
A flexible and stable photodetector shows great potential applications in intelligent wearable devices, health monitoring, and biological sensing. The high-output fabrication of flexible and stable photodetector via the large-scale printing process would accelerate its commercialization. Herein, a high performance, flexible organic bulk heterojunction (BHJ) photodetector with good stability is designed and fabricated via a large-scale roll-to-roll (R2R) micro-gravure printing technique on polyethylene terephthalate (PET) or paper substrate, in which the organic BHJ active layer is structured with [6,6]-phenyl C61 butyric acid methyl ester (PCBM) and a donor–acceptor copolymer, i.e., employing 4,8-bis(2-ethylhexylthiophene) benzo[1,2-b;3,4-b′] dithiophene (BDTT) as the donor unit and 5,8-bis(5-thiophen-2-yl)-6,7-difluoro-2,3-bis(4-ethylhexyloxy-1-mata-luorophenyl) quinoxaline (ffQx) as the acceptor unit (PBDTT-ffQx). The PBDTT-ffQx/PCBM BHJ photodetector shows a broad photoresponse in ultraviolet and visible light, a high detectivity (D*) value up to 6.19 × 1011 Jones, and an excellent Iphoto/Idark as high as 5.6 × 102. It exhibits excellent flexibility and stability. Its performance parameters could maintain over 80% of original values after bending 10,000 cycles or exposing in ambient condition (humidity ~50%, temperature ~30 °C) for 50 days without any encapsulation. More importantly, the R2R micro-gravure printed PBDTT-ffQx/PCBM BHJ active layer is great homogeneous, and the responsivity (R) values of photodetector arrays show a very narrow distribution. The research results show that a high-performance PBDTT-ffQx/PCBM BHJ photodetector with well reliability and reproducibility can be fabricated via the R2R micro-gravure printing technique, which provides an available strategy for fabricating large-area and flexible electronic and optoelectronic devices.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.