At LPS we have explored organic bulk heterojunctions for photodetector applications and find that interface layers that are typically incorporated into photovoltaic device structures to optimize their performance result in optical loss that lowers the photodetector responsivity. Removal of these interfaces leads to higher efficiency and simplified device design of organic photodetectors as shown in the figure below.. This is explained by the results of the model calculation of the optical field within the devices showing the optical loss associated with the presence of the interface layers.
Improved photodetector performance of device #2 with no interface layers
compared to a device #1 with interface layers on both electrodes.
“Interface Effects on the External Quantum Efficiency of Organic Bulk Heterojunction Photodetectors”, Y. Kim, M. Ballarotto, D.H. Park, M. Du, W.L. Cao, C. H. Lee, W. N. Herman, and D. B. Romero, Applied Physics Letters 91, 193510(2007).