A Multi-Parameter Sensor Based on Cascaded Photonic Crystal Cavities Filled with Magnetic Fluid

A kind of photonic crystal (PC) micro-cavity sensor based on magnetic fluid (MF) filling is designed with simulation model. Generally, many sensors’ designs are based on a universal temperature in the whole structure. However, strong photothermal effect in high Q micro-cavities will lead to different temperatures between cavities and environment inevitably. In many theoretical PC sensor designs, researchers neglected the different temperature between environment and cavities. This simple hypothesis will probably lead to failure of sensor design and get wrong temperature. Moreover, few theoretical or experimental works have been done to study optical cavity’s heating process and temperature. We propose that researchers should take seriously about this point. Here, the designed cascaded micro-cavity structure has three spectral lines and a reversible sensitivity matrix, which can simultaneously detect magnetic field, ambient temperature and MF micro-cavity temperature. It can solve the magnetic field and temperature cross-sensitivity problem, and further, distinguish the different temperatures of environment and magnetic fluid cavities. The influence of hole radius and slab thickness on the depth and Q value of the resonant spectral line are also studied. Responses of three dips to magnetic field, ambient temperature and MF micro-cavity temperature are simulated, respectively, where dip 1 belongs to MF cavity 1, dip 2 and dip 3 belong to MF cavity 2. The obtained magnetic field sensitivities are 2.89 pm/Oe, 4.57 pm/Oe, and 5.14 pm/Oe, respectively;the ambient temperature sensitivities are 65.51 pm/K, 50.94 pm/K, and 58.98 pm/K, respectively;and the MF micro-cavity temperature sensitivities are −14.41 pm/K, −17.06 pm/K, and −18.81 pm/K, respectively.

Short-axis substitution approach on ladder-type benzodithiophene- based electron acceptor toward highly efficient organic solar cells

Short-axis substitution, as an effective way to change the optical and electronic properties of the organic semiconductors for organic photovoltaics(OPVs), is a readily approach to modify non-fullerene acceptors, especially for the linear fused rings system. Here, two new fused-ring electron acceptors(CBT-IC and SBT-IC) were designed and developed by short-axis modification based on the dithienyl[1,2-b:4,5-b′]benzodithiophene(BDCPDT) system. Combined with a medium bandgap polymer donor J71, both of the OPV devices exhibit high power conversion efficiency(PCE) over 11%, and ～70% external quantum efficiencies. To better understand how this kind of substitution affects the BDCPDT based acceptors, a comparative analysis is also made with the the plain acceptor BDT-IC without this modification. We believe this work could disclose the great potential and the versatility of BDCPDT block and also enlighten other ladder-type series for further optimization.