Tetrahydroquinoxaline Based Small Molecule: PCBM Bulk Heterojunction Solar Cell

We have fabricated solution processed bulk heterojuction (BHJ) solar cell from small molecule (SM) as donor blended with PCBM as an acceptor. The BHJ showed power conversion efficiency (PCE) up to 2.80 %. The PCE has been further improved up to 3.80 % after thermal annealing of the SM: PCBM layer. The higher PCE of the photovoltaic devices based on the thermal annealed SM: PCBM blend as compared to SM: PCBM blend is attributed to the increase in the crystalline nature of the blend and hole mobility. The thermal annealing allows not only a broad absorption but also tuning of the inter energy level leading to a higher short circuit current (Jsc) and open circuit voltage (Voc).