Exciton dissociation and charge transport are important processes in the photoelectric conversion of organic solar cells (OSCs), directly affecting the performance of OSCs. In order to facilitate exciton dissociation, phase separation size should be as small as possible. However, for the sake of continuous charge transport, a large phase separation size is also necessary. To balance these two conflicting needs, it is of utmost importance to regulate the phase separation of the active layer. This Review mainly elaborated the smart tactics commonly adopted to phase separation optimization, aiming to understand how these treatments affect both the active layer phase separation and the performance of OSCs. Furthermore, we present an outlook on the new opportunities of phase separation regulation of the active layer. Finally, this Review may provide some reference for the researchers engaged in the research of OSCs.

The features of upper-air visibility at altitudes of 0.1, 0.3, and 0.5 km and the two-dimensional haze characteristics in the northwest of downtown Beijing were studied by using a multi-platform analysis during haze episodes between 17 December 2016 and 6 January 2017. Through the multi-platform data analysis in hourly and daily variation, the upper-air visibility increased along with the decrease of PM_2.5 mass concentration. And the upper-air visibility on non-haze days was about 3–5 times higher than that on haze days with the ground-based Raman–Mie lidar data between 13 December 2016 and 11 January 2017. The vertical transport of pollutants can be inferred from the delayed variation of upper-air visibility between high altitude and low altitude. In addition, the two-dimensional haze characteristics could be studied by analyzing the correlation between vertical haze parameters (atmospheric boundary layer, haze thickness, and aerosol optical thickness) and horizontal haze parameter (upper-air visibility). The characteristics of multi-parameters have been analyzed and concluded for different haze levels.

Aerosol lidar ratio (LR) is important for inversion of aerosol optical characteristics. Single aerosol LR value adopted in the inversion not only causes difficulties in improving aerosol inversion accuracy but also hinders the analysis of aerosol types. In this paper, a pseudo-constant method with certain universality is proposed for inverting aerosol LR profiles. Simulation results show a decrease in the mean absolute error (MAE) of the aerosol LR from 3.57% (iteration method) and 9.96% (Fernald method) to 1.82% (pseudo-constant method). In the near-surface region (<1.5 km), the MAE of aerosol LR decreases from 4.97% (iteration) and 21.66% (Fernald) to 1.54% (pseudo-constant). Moreover, the inversion accuracy of aerosol LR obtained from pseudo-constant method is less influenced by the precision of the pre-estimated aerosol LR value than that from iteration method. Experimentally, the aerosol LR and aerosol extinction coefficient profiles obtained from the pseudo-constant method are more accurate than those from the iteration and Fernald methods. In addition, both the simulations and experiments indicate that the pseudo-constant method has higher efficiency; the processing time is shortened from approximately 5 s per signal (iteration) to approximately 0.1 s per signal. Finally, aerosol types can be distinguished to a certain degree by combining the improved aerosol LR profile.