The additive engineering to hybrid organic‐inorganic perovskite precursors is an effective technique toward highly efficient stable photovoltaic devices, however, there is still a deficiency in fundamental understanding on how these additives affect the perovskite film and device performance as well. Herein is introduced a small organic molecule, DRCN5T, into a double‐cation perovskite precursor and the function on device performance is systematically investigated. An appropriate amount of DRCN5T into the precursor can promote the crystallization of film with successful suppression of δ‐FAPbI3 phase, reduce grain boundaries and adequately passivate the native defect sites. In addition, the incorporation of DRCN5T also regulates the energy level alignment of the perovskite to charge transport layer suitably. This leads to the promotion of charge transport, reduction in non‐radiative recombination, and boosts the efficiency to a value of 20.60% with greatly reduced hysteresis in the device. Moreover, the treatment by DRCN5T also significantly increases the stability of the devices in ambient environment. These findings open the gate to produce highly crystallized perovskite/organic‐molecule active layers toward commercialization of perovskite solar cells.

We presented a novel technique to design microlens optical beam homogenizing system for excimer lasers. As a new approach by applying freeform surface microlens array, the homogenizer can yield somehow superior beam shaping results with larger but less microlens units than conventional method. With new concept and design, the diffraction effects at the microlens apertures can be reduced substantially. Large scale and highly uniform beam profile can be realized at a relative nearby working distance after beam shaping. This is hard to achieve by conventional method. Our design method takes the real spatial energy characteristics of the excimer laser beam as the design basis, and combined with feasible optimization method. The design method is demonstrated as a real instance based, on a 193 nm ArF excimer laser in our laboratory. Moreover, to verify the effectiveness of our method, the designed freeform microlens array homogenizer has been fabricated and tested experimentally. The experimental optical performance of the homogenizer coincides well with the theoretical simulation.

Antimony selenosulfide, Sb 2 (SSe) 3 , is recognized as an excellent photoactive material owing to its light harvesting capability. There is still room for improvement of the film quality for device performance improvement. Herein, an organic chloride salt [diethylamine hydrochloride, DEA(Cl)] has been introduced for fabricating Sb 2 (SSe) 3 solar cells for the first time. A champion device with a power conversion efficiency (PCE) of 9.17% has been achieved with a relatively improved fill factor and open-circuit voltage (V OC ). It has been revealed that DEA(Cl) successfully interacts with Sb 2 (SSe) 3 , which can facilitate the crystallization process to give rise to the closely packed bigger grain sizes with reduced surface cracks; it successfully suppressed the oxidized Sb species (Sb 2 O 3 ) in the Sb 2 (SSe) 3 film to give rise to phase purity, thus leading to superior surface morphology and electrical characteristics of DEA(Cl)-modified Sb 2 (SSe) 3 absorber films. Chloride modification is thus efficiently helpful in suppressing interfacial defects, improving junction quality, and optimizing energy-level alignment. This facile interfacial modification demonstrates the remarkable potential for efficient Sb 2 (SSe) 3 solar cells.

Organic–inorganic hybrid perovskite photodetectors are gaining much interest recently for their high performance in photodetection, due to excellent light absorption, low cost, and ease of fabrication. Lower defect density and large grain size are always favorable for efficient and stable devices. Herein, we applied the interface engineering technique for hybrid trilayer (TiO2/graphene oxide/perovskite) photodetector to attain better crystallinity and defect passivation. The graphene oxide (GO) sandwich layer has been introduced in the perovskite photodetector for improved crystallization, better charge extraction, low dark current, and enhanced carrier lifetime. Moreover, the trilayer photodetector exhibits improved device performance with a high on/off ratio of 1.3 × 104, high responsivity of 3.38 AW−1, and low dark current of 1.55 × 10−11 A. The insertion of the GO layer also suppressed the perovskite degradation process and consequently improved the device stability. The current study focuses on the significance of interface engineering to boost device performance by improving interfacial defect passivation and better carrier transport.

The development of high-crystalline perovskite films with large crystal grains and few surfacedefects is attractive to obtain high performance perovskite solar cells (PSCs) with good device stability. Herein, we simultaneously improve the power conversion efficiency (PCE) and humid stability of the CH 3 NH 3 PbI 3 (CH 3 NH 3 =MA) device by incorporating small organic molecule IT-4F to the perovskite film and using buffer layer of PFN-Br. The presence of IT-4F in the perovskite film can successfully improve crystallinity and enhance grain size, leading to reduced trap states, longer lifetime of charge carrier and make perovskite film hydrophobic. Meanwhile, as a buffer layer, PFN-Br can accelerate the separation of exciton and promote the collection process of electrons from active layer to cathode. As a consequence, the PSCs present a remarkably improved PCE to 20.55% with reduced device hysteresis. Moreover, the moisture resistive film based devices retain about 80% of its initial efficiency after 30 days of storage in relative humidity (RH) of 10-30% without encapsulation.