Doping highly ordered organic semiconductors: experimental results and fits to a self-consistent model of excitonic processes, doping, and transport.

An in-depth study of n-type doping in a crystalline perylene diimide organic semiconductor (PPEEB) reveals that electrostatic attractions between the dopant electron and its conjugate dopant cation cause the free carrier density to be much lower than the doping density. Measurements of the dark currents as a function of field, doping density, electrode spacing, and temperature are reported along with preliminary Hall-effect measurements. The activation energy of the current, E(aJ), decreases with increasing field and with increasing dopant density, n(d).

[Eighteen years activity in prevention of blindness in the district of Shunyi, Beijing].

Objective: To investigate how the urban tertiary hospital and medical research unit cooperate with rural basic medical unit in creating the model zone in prevention of blindness.

Methods: Peking Union Medical College Hospital (PUMCH) and Shunyi District Bureau of Public Health exerted their advantages to persist and popularize the program for prevention of blindness. A collaborative program in prevention of blindness was conducted by PUMCH and Shunyi District Bureau of Public Health.