Effects Of Morphology Engineering On The Performance Of Organic Solar Cells And Perovskite Solar Cells

Recently,the power conversion efficiencies(PCEs)of organic solar cells and perovskite solar cells have increased dramatically.Many researches were dedicated to pursuing the solar cells with higher performance from different aspects,including interfacial engineering,composition engineering,solvent engineering,morphological regulations of active layers and so on.The optimization of the morphologies of the active layers is a key factor in improving the performance of the device both for organic and perovskite solar cells.In this thesis,the active layer morphologies of organic solar cells and perovskite solar cells were optimized in two different ways,and device performance was consequently improved.The details are as follows:(1)Ternary organic solar cells(OSCs)are an effective strategy to optimize the morphologies of active layers and achieve high power conversion efficiencies(PCEs)by incorporating a third component with a complementary absorption into the binary blends.In this work,DR3 TBDTTVT,a newly designed two-dimensional-conjugated small molecule,mixed with PC71 BM as active layer and the OSC based on DR3TBDTTVT:PC71BM obtained a PCE of 5.71%.Given the complementary absorption and well-matched energy levels with PTB7-Th and PC71 BM,DR3TBDTTVT was doped into the blends of PTB7-Th:PC71BM,and a series of ternary OSCs were prepared.The ternary OSCs with 10 wt% of DR3 TBDTTVT exhibited improved hole-mobility,reduced device resistance and better phase separation of active layer,thus leading to an improved PCE of 7.77% with open-circuit voltage(Voc)of 0.77 V,short-circuit current density(Jsc)of 14.52 m A/cm2 and fill factor(FF)of 70.3%.Ternary OSCs well complement for the light-harvesting insufficiency of binary OSCs,and this work provides a novel material candidate for high efficient single-junction OSCs.(2)The morphological optimizations of perovskite films have been developed as an efficient tool to enhance the PCEs of perovskite solar cells(Pero-SCs).Up to date,additives was proved to be a broadly accepted method to regulate the crystallization behavior of perovskite.Herein,we introduce a molecule of 3,4-dihydroxybenzhydrazide(DOBD)containing Lewis base C=O group into perovskite to control the crystallization kinetics.With the doping of DOBD,the perovskite presented larger grain size and fewer grain boundaries,which were beneficial to facilitate charge transportation and suppress charge recombination.The PCE of DOBD doped Pero-SC skyrocketed to 17.58% with an enhanced Voc of 1.06 V,Jsc of 21.40 m A/cm2 and FF of 79.1%,and the PCE was much higher than that of Pero-SC without DOBD(14.47%).Moreover,the stabilities of DOBD doped-Pero-SCs also acquired a great improvement.This research demonstrated that the suitable additives could contribute to further improvements for high-performance Pero-SCs.