Device Physics In Novel Solar Cells

Organic–inorganic halide perovskite is very promising candidate for future photovoltaic society because its high percent that can be available from inexpensive and high-throughput solution process.Meanwhile,organic solar cells(PSCs)have attracted much attention in the world as a novel and renewable energy resource technology due to their advantages of low cost,easy fabrication,light weight,and the capability to fabricate flexible large-area devices.The main results are as follows:1.The effects of steady-state charge transport and relevant opto-electrical properties on the solar cell performance in solution processed methylammonium lead triiodide(MAPb I3)perovskite films with inverted planar architecture were investigated.By tuning MAPb I3 film thickness(L),observe systematic variations of the charge carrier mobility,trap density,and charge recombination in MAPb I3 solar cells which lead to modulation of the device parameter.The results suggest that charge carrier mobility may not be a limiting factor for the photocurrent losses in MAPb I3 solar cells while traps indeed play a role in the solar cell behavior.This work provides fundamental insights into opto-electrical properties governing the device characteristics in solution-processed MAPb I3 solar cells.2.In this work,ZnO nanoparticles which are incorporated as an ETL/HBL into polymer solar cells comprising of PTB7-Th donor in blend with PC71 BM acceptor.We investigate the influences of processing for Zn O nanoparticle ETLs,and resultant device behaviour and stability.We found that the polarity of the processing solvents and thickness of Zn O nanoparticles thin films play a crucial role in the device behavior.In the optimal condition,the power conversion efficiency(PCE)is increased from 8.4% to 9.2% for PTB7-Th:PC71BM solar cells.3.Temperature(T)-dependent charge transport and bimolecular recombination were comparatively investigated based on three BHJs comprising of non-fullerene ITIC and p(NDI2OD-T2)electron acceptors along with PC71 BM blended with the polymer donor of PBDB-T.We found that even with an imbalanced transport and reduced electron mobility,the solar cell based on PBDB-T:ITIC blends produces the highest PCE approaching 10%,primarily due to an enlarge short-circuit current(Jsc).The photoconductivity of these BHJs cannot be purely interpreted by the absorption and transport characteristics of respective films but clearly correlates to the trend of recombination strength.The gain in Jsc for the device with ITIC can be primarily ascribed to the lowering in reduction factor(?)and resultant decrease in the recombination coefficient(krec).Interestingly,the ?approximately correlates to the balance of mobility in the BHJs.In comparison to the relatively small activation energy(Ea)for the transport(50-150 me V),due to strong ordering in molecular stacking,a larger Ea is identified for krec and ?,which suggests that other factors may play a role in the thermal activation for bimolecular recombination.Our results point to an indication that the mobility balance and electron mobility to some degree may not be a severe limitation for the photovoltaic behavior,at least based on BHJs with ITIC acceptor.On the other hand,to further advance the performance in non-fullerene based solar cells,a suppression on the recombination strength is essential.