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.

Br, I) have attracted much attention due to their superior photoelectric properties, for example, direct band gap (≈1.6 eV), small exciton binding energy (≈20 meV), broad absorption range, long-range exciton diffusion length (100-1000 nm). [7][8][9] Thus they play as important candidates in the field of renewable photovoltaic or photoelectric devices. [10][11][12][13] Perovskite materials were introduced into solar cells in 2009 with the power conversion efficiencies (PCEs) of about 3.81%, and the PCEs of state-ofthe-art perovskite solar cells have been over 20.0%. [14][15][16][17] Furthermore, perovskitebased photodetectors are being quickly developed as well. [18][19][20] The interface engineering using suitable interface materials is a powerful approach to improve the performance of perovskite photodetectors. [21][22][23][24][25] The graphene/perovskite hybrid photodetectors produced high performance with a responsivity up to 180 A W −1 , [23] and a monolayer graphene covered with a thin layer of dispersive perovskite islands resulted in an ultrahigh responsivity photodetector (≈6.0 × 10 5 A W −1 ). [26] However, the ratio of photocurrent and dark current (I light /I dark ) of these perovskite-based photodetector is very small, which is normally lower than 10. Very recently, it was reported that the CH 3 NH 3 PbI 3 /WS 2 heterostructure photodetectors could produce an I light /I dark of ≈10 5 and a responsivity of ≈17 A W −1 . [25] Organic semiconductor materials have the advantages of simple synthesis, low cost, large-scale, and low-temperature fabrication process, showing the great potentials for next-generation flexible electronic and photoelectronic devices. [27][28][29][30] Chen and co-workers demonstrated a photodetector based on CH 3 NH 3 PbI 3 and conjugated polymer (PDPP3T), of which the lifetime and stability were obviously improved owing to the protection of organic layer, while the performance parameters did not show obvious improvement, probably resulting from the low mobility of PDPP3T. [31] Dioctylbenzothieno [2,3-b] benzothiophene (C8BTBT) is an excellent organic semiconductor material with good air stability and ultrahigh hole carrier mobility. [32,33] Herein, we demonstrate that a CH 3 NH 3 PbI 3 / C8BTBT heterojunction produced by solution-processable method could be effectively used to fabricate high-performancePerovskite photodetectors are fabricated via structuring a perovskite/organic heterojunction with CH 3 NH 3 PbI 3 and a high-mobility and stable organic semiconductor dioctylbenzothieno [2,3-b] benzothiophene (C8BTBT), which possess broad range photoresponse from ultraviolet to near-infrared, fast response, and excellent stability. The CH 3 NH 3 PbI 3 /C8BTBT heterojunction photodetectors exhibit an excellent ratio of photocurrent to dark current, I light /I dark , as high as 2.4 × 10 4 , a high responsivity up to 24.8 AW −1 , and a fast response of about 4.0 ms. Meanwhile, the photodetectors can maintain 90% performance even exposed in ambient condition without encapsulation for 20 ...

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.

No abstract

Thin-film transistors (TFTs) have experienced tremendous development during the past decades and show great promising applications in flat displays, sensors, radio frequency identification tags, logic circuit, and so on. The printed TFTs are the key components for rapid development and commercialization of printed electronics. The researchers in China play important roles to accelerate the development and commercialization of printed TFTs. In this review, we comprehensively summarize the research progress of printed TFTs on rigid and flexible substrates from China. The review will focus on printing techniques of TFTs, printed TFT components including semiconductors, dielectrics and electrodes, as well as fully printed TFTs and printed flexible TFTs. Furthermore, perspectives on the remaining challenges and future developments are proposed.